LIBRARY 

OF   THE 

UNIVERSITY  OF  CALIFORNIA. 


Class 


THE 

PRODUCTION  OF  ALUMINUM 

AND  ITS 

INDUSTRIAL   USE. 


BY 

ADOLPHE    MINET, 

Officer  of  Public  Instruction  and  Editor  of  "  L' Electrochimie™ 


TRANSLATED,    WITH      ADDITIONS, 

BY 

LEONARD  WALDO,   S.D.   (HARV.) 


FIRST    EDITION. 

FIRST  THOUSAND. 
^^^^\B  R  A  njr**1^ 

[         "   OF  THE 

(    UNIVERSITY 

or 


JOHN  WILEY  AND  SONS. 

LONDON:  CHAPMAN  &  HALL,  LIMITED. 

1905. 


Copyright,  1905, 

BY 

LEONARD  WALDO. 


ROBERT   DRUMMOND,    PRINTRR,    NEW   YORK. 


AUTHOR'S  PREFACE  TO  THE  AMERICAN 
EDITION. 


THE  present  work  comprises  a  principal  part, 
which  is  a  literal  translation  of  the  German  edition 
"  Die  Gewinnung  des  Aluminiums  und  dessen 
Bedeutung  fur  Handel  und  Industrie,"  published 
in  1902,  and  an  appendix  including  two  wholly  new 
chapters:  the  first,  by  the  Author,  is  devoted  to  a 
supplementary  consideration  of  those  parts  of  the 
German  edition  which  have  been  made  the  subject 
of  criticism;  in  the  second  chapter,  Dr.  Leonard 
Waldo  describes  the  developments  in  the  Aluminum 
industry  of  recent  years,  more  especially  in  the 
United  States — a  matter  which  the  limited  scope 
of  the  first  book  had  compelled  me,  greatly  to 
my  regret,  to  overlook. 

I  am  sure  that  Dr.  Waldo's  contribution  will 
meet  with  a  favorable  reception  on  the  part  of  the 
reader,  and  that  his  twofold  collaboration  (since 
he  is  also  the  translator)  will  contribute  in  large 
measure  to  ensure  popular  interest  in  the  monograph. 

I  desire  also  to  express  my  thanks  to  the  Messrs. 
Wiley  and  Sons  for  their  promptly  executed  and 
painstaking  labor  in  publishing  the  work. 

ADOLPHE   MINET. 

PARIS,  January,  1905. 

ill 

142409 


CONTENTS. 


PART   I. 
PROCESSES  FOR   THE  PRODUCTION   OF   ALUMINUM. 

PAGE 

A.  Chemical  Method  of  Producing  Aluminum 2 

a.  Processes  based    on   the  Reduction   by  means  of 

Sodium 3 

b.  Processes  which  do  not  Employ  Sodium 14 

B.  Electrochemical  Methods  of  Producing  Aluminum 17 

a.  Ele'ctrothermic  Processes 21 

b.  Electrolytic  Processes  for  the  Production  of  Alu- 

minum      56 


PART   II. 

ALUMINUM    AND   ITS    ALLOYS,    METHODS   OF 
WORKING  AND    USES. 

A.  The  Aluminum  Industry 136 

B.  Aluminum  and  its  Alloys 144 

a.  Pure  Aluminum 144 

b.  Heavy  Alloys  147 

c.  Alloys  of  Medium  Density 155 

d.  Alloys  of  Various  Densities 157 

e.  Light  Alloys  1 62 


Vl  CONTENTS. 

PAGE 

C.  Working  of  Aluminum : 171 

Process  for  Soldering  Aluminum 175 

Electroplating  of  Aluminum 1 86 

D.  Uses  of  Aluminum  191 

a.  In  Commerce  and  Minor  Industry 192 

b.  In  Greater  Industry J92 

c.  In  Chemistry  and  Metallurgy 201 

Aluminothermy 207 

APPENDIX. 

SUPPLEMENTARY  NOTES  BY  ADOLPHE  MINET. 

Industrial  Questions 218 

The  Theoretical  Part 224 

ALUMINUM     IN     THE     UNITED    STATES. 
SUPPLEMENTARY  NOTE  BY  THE  TRANSLATOR.  . . ,  241 


.   . 
PRODUCTION    OF    ALUMINUM. 


PART  I. 

PROCESSES     FOR     THE     PRODUCTION    OF 
ALUMINUM. 

ALUMINUM  is  found  in  nature  as  oxide  (A12O3) 
in  corundum,  sapphire,  and  emery;  as  hydroxide 
(Al2(OH)6)  in  bauxite,  hydrargillite,  and  diaspore; 
in  the  form  of  salts  in  cryolite  (an  aluminum-sodium 
double  fluoride  with  the  composition  Al2F6.6NaF), 
in  alum,  in  the  felspars,  in  slate,  and  in  clay. 

The  number  of  processes  devised  up  to  the 
present  time  for  the  production  of  aluminum  is 
very  large,  but  only  a  few  have  attained,  in  their 
application,  an  industrial  significance.  They  may 
be  divided  into  two  great  and  distinctly  separate 
classes : 

(A)  Chemical  Methods.  To  this  class  belong 
the  processes  devised  by  Wohler,  Henry  Sainte- 
Claire  Deville,  Castner,  Netto,  Grabau,  Webster, 
Frismuth,  etc. 


2  .       PRODUCTION   OF  ALUMINUM. 

(B),  Electrochemical  Methods.  These  may  be 
divided  into  two  groups: 

(a)  Electrothermic    Processes    (Cowles,    Heroult, 
Brin,  Bessemer,  Stefanite,  Moissan  with  his  alumi- 
num-carbide) . 

(b)  Electrolytic  Processes;  namely,  those  devised 
by  Heroult,  Adolphe  Minet,  Hall,  Hampes,  Kleiner, 
Gooch,  and  Waldo. 

A.  CHEMICAL  METHOD  OF  PRODUCING  ALUMINUM. 

Aluminum  was  isolated  for  the  first  time  in  the 
year  1827  by  Wohler,*  who  produced  it  impure  and 
in  small  quantities  by  means  of  the  effect  of  potas- 
sium upon  anhydrous  aluminum  chloride. 

All  attempts  previously  made  by  Davy,  Berzelius, 
and  Oerstedt  to  decompose  the  clay  by  means  of 
the  electric  current  had  not  yielded  the  result  which, 
since  the  successful  electrolytic  dissociation  of  the 
alkali  hydroxides,  might  confidently  be  expected. 

Oerstedt  t  had  attempted,  shortly  after  his  dis- 
covery of  aluminum  chloride,  to  reduce  this  sub- 
stance by  means  of  alkali  metals,  which  he  allowed 
to  act  in  the  form  of  amalgams.  This  was  likewise 
without  result. 

This  noteworthy  method,  which  is  the  first 
example  of  a  reduction  between  anhydrous  bodies 

*  Poggendorffs  Annalen,  XI,  1827,  and  Liebigs  Annalen, 
LIII. 

t  Overs,  o.  d.  Danske  Vidensk.  Selsk.  Forhandl.  1824-1825. 


PROCESSES.  3 

fused  by  melting,  was  to  be  successful  for  the  first 
time  in  the  hands  of  Wohler,  who,  as  we  know, 
isolated  beryllium  and  zirconium  as  well  as  alumi- 
num. 

The  aluminum  Wohler  obtained  in  the  year  1827 
consisted  of  a  whitish-gray  powder  having  all  the 
physical  characteristics  of  the  metals;  not  until 
the  year  1845  did  he  succeed  in  obtaining  aluminum 
in  the  form  of  ductile  pellets,  so  that  from  these  he 
could  determine  the  most  important  physical  and 
chemical  characteristics  of  aluminum.  It  was  still, 
however,  far  from  possible  to  consider  aluminum 
as  one  of  the  common  metals. 

This  consummation,  the  result  of  a  comprehen- 
sive investigation  of  aluminum,  which  was  now 
about  to  be  obtained  for  the  first  time  in  a  per- 
fectly pure  condition,  was  reserved  for  Henry 
Sainte-Claire  Deville  *  (1854). 

To  Deville,  furthermore,  we  owe  the  first  attempt 
to  produce  aluminum  by  the  use  of  metallic  sodium ; 
a  method  whose  principle  is  that  of  a  great  number 
of  later  patents. 

a.  Processes  based  on  the  Reduction  by  means  of  Sodium. 

Henri  Sainte-Claire-Deville  Process. — The  first 'Suc- 
cessful improvement  made  by  Deville  consisted 
in  the  replacement  of  potassium  by  sodium; 
hitherto,  following  the  example  of  Wohler,  potas- 

*  Annales  de  chimie  et  physique,  XLIX,  1854,  and  St.  Claire 
Deville,  de  L' Aluminium,  Paris,  1855. 


4  PRODUCTION  OF  ALUMINUM. 

slum  had  invariably  been  employed  as  a  reducing- 
agent.  For  the  aluminum  salt,  Deville  adhered  to 
the  aluminum  chloride  usually  employed. 

Thanks  to  the  labors  of  Briinner,  Mitscherlich, 
Donny,  and  Mareska  in  the  production  of  potas- 
sium and  sodium,  Deville  was  enabled  to  make  for 
himself  without  difficulty  considerable  quantities 
of  sodium,  and  at  the  same  time  to  reduce  large 
amounts  of  aluminum  chloride.  To  this  fact,  in 
the  main,  the  final  result  of  his  investigations  was 
due. 

In  the  mean  time  still  other  obstacles  were  en- 
countered in  the  industrial  production  of  alumi- 
num. Apart  from  the  fact  that  it  was  necessary 
to  produce  great  quantities  of  sodium  quickly  and 
cheaply,  two  other  industries  must  spring  into  being 
hand  in  hand  with  the  manufacture  of  aluminum: 
the  production  and  the  refining  of  alumina,  and 
the  conversion  of  this  aluminum  oxide  into  an- 
hydrous chloride;  to  these  two  processes  was  added 
the  reduction  of  the  chloride  by  means  of  an  alkali- 
metal. 

We  must  not  omit  to  add  that,  at  the  time  of  the 
above-mentioned  investigations  of  Deville,  a  min- 
eral rich  in  aluminum — cryolite  (aluminum-sodium 
double  fluoride) — was  discovered  in  Greenland. 
Deville  employed  this  salt  as  a  flux,  adding  it  in 
various  proportions  to  the  anhydrous  aluminum 
chloride,  and  found  that  the  chemical  reaction  took 
place  more  readily  in  the  presence  of  cryolite. 


PROCESSES.  5 

The  researches  of  Deville  were  begun  in  the 
Sorbonne  in  the  year  1854.  The  first  industrial 
investigations  were  carried  out  in  the  establish- 
ment of  Rousseau  in  "la  Glaciere,"  and  were  later 
continued  in  Nanterre  under  Morris's  direction. 

Up  to  the  present  time,  Deville's  process  was 
employed  in  Salindres,  where,  on  the  average, 
2000  kg.  aluminum  was  produced  yearly.  The 
selling-price,  however,  was  rarely  below  100  francs 
per  kilogram. 

Rose  Process. — In  the  year  1856  the  brothers 
Tessier  established  a  factory  in  Amfreville  near 
Rouen,  in  which  aluminum  was  produced  by  a 
process  which  had  been  recommended  by  Rose,* 
and  which  depended  exclusively  upon  the  reduc- 
tion by  cryolite,  a  method  which  had  been  dis- 
covered by  Dr.  Percy  in  the  year  1855, — a  year 
later,  then,  than  Deville's  investigations.  We 
should  add,  as  a  matter  of  historic  interest,  that 
before  the  erection  of  their  factory  the  brothers 
Tessier  had  studied  the  question  of  producing 
aluminum  in  H.  St.-C.  Deville's  own  laboratory. 

Castner  and  Netto  Processes.  —  These  processes 
rest  upon  the  same  principle  as  that  of  Deville; 
from  an  industrial  point  of  view,  however,  they 
show  a  considerable  improvement  upon  the  latter, 
since  the  price  of  aluminum  produced  according  to 
the  new  method  fell  below  20  francs  per  kilogram. 

*  Poggendorffs  Annalen,  XCVI,  1855. 


6  PRODUCTION  OF  ALUMINUM. 

Castner  Process.* — This  process,  which  was  em- 
ployed about  1899  by  the  Aluminum  Company, 
Limited,  in  Oldbury,  Birmingham,  shows  substantial 
improvements,  mainly  in  two  directions:  (i)  in 
the  production  of  the  sodium  with  the  aid  of  caustic 
hydrate  of  soda  at  a  low  temperature,  and  (2)  in 
the  production  of  aluminum-sodium  double  chloride. 

Production  of  Sodium. — Castner  obtains  sodium 
from  caustic  hydrate  of  soda  with  the  aid  of  an 
artificial  iron  carbide  at  a  temperature  which  does 
not  exceed  iooo°C.,  and  which  is,  therefore,  con- 
siderably lower  than  the  temperature  reached  by 
Deville.  The  latter  availed  himself  in  this  case 
of  the  classic  method  of  reduction,  with  soda,  by 
means  of  carbon. 

The  composition  of  the  iron  carbide  employed 
is  expressed  in  the  formula  FeC2;  from  7  to  8  kg 
carbide  were  mixed  with  12  kg  caustic  hydrate  of 
soda,  and  gave  as  a  product  of  reaction  2  kg  sodium, 
according  to  the  equation 

6NaOH  +  FeC2  =  6Na  +  Fe  +  CO  +  C02 

The  iron  in  this  process,   then,  merely  plays  the 
part  of  an  intermediary  substance. 

Production  of  Aluminum-sodium  Double  Chloride. 
— The  difficulty  in  this  process  is  to  secure  a  steady 
supply  of  chlorine  gas.  The  chlorine,  generated 

*  Cf.  U Aluminium,  fabrication  et  emploi,  by  Adolphe  Minet, 
pp.  127-137. 


PROCESSES.  7 

by  the  Weldon  process,  is  first  collected  in  lead 
gasometers,  and  then  conducted  over  a  mixture 
of  clay,  carbon,  and  common  salt,  which  is  con- 
tained in  a  horizontal  retort  3.6  m  in  length;  the 
retort  is  heated  by  means  of  gasoline  gas.  The 
mixture  containing  aluminum  is  dephlegmated  in 
the  apparatus  even  before  it  is  treated  with  chlorine, 
and  the  resulting  aluminum-sodium  chloride,  accord- 
ing to  the  form  and  proportion  it  takes,  is  condensed 
in  brick  receptacles. 

However  pure  the  material  from  which  it  is 
derived  may  be,  the  chloride  produced  in  the 
method  described  will  still  be  found  to  include, 
invariably,  considerable  quantities  of  iron;  and 
since  the  weight  of  the  chloride  should  be  about 
ten  times  as  great  as  the  weight  of  the  aluminum 
produced,  it  follows  that  the  metal  obtained  in 
this  manner  would  contain  far  too  large  a  propor- 
tion of  iron,  were  not  the  double  chloride,  before 
it  is  decomposed  by  sodium,  subjected  to  a  special 
purification.  This  consists  in  melting  it  with  a 
small  quantity  of  aluminum-  and  sodium-powder. 
The  proportion  of  iron,  which  in  many  cases  origi- 
nally  amounts  to  i  %,  is  decreased  by  this  treatment 
to  0.1%. 

Another  method  for  purifying  the  double  chlo- 
ride depends  upon  its  treatment  electrolytically :  a 
method  likewise  proposed  by  Castner. 

Reduction  of  the  Aluminum  Chloride.  —  The 
chloride  is  mixed  with  cryolite  in  the  proportion 


PRODUCTTON  OF  ALUMINUM. 

2:1,  with  the  addition  of  small  pieces  of  sodium; 
the  whole  is  then  mixed  in  a  rotating  cylinder, 
which' is  introduced  into  an  air-furnace  previously 
heated  to  the  temperature  of  reaction.  The  charge 
consists  usually  of  550  kg  double  chloride,  150  kg 
cryolite,  and  150  kg  sodium.  The  quantity  of 
aluminum  obtained  by  means  of  a  single  operation 
amounts  to  about  60  kg. 

Netto  Process.*  —  This  process  was  operated  by 
the  Alliance  Aluminium  Company  in  Wallsend  at 
Newcastle,  and,  indeed,  simultaneously  with  Cast-' 
ner's  process.  Netto's  method  is  a  modification 
of  the  old  cryolite  process,  as  it  was  first  proposed 
by  Deville,  and  industrially  introduced  by  Rose  and 
Percy  in  the  year  1885.  It  depends  upon  the  reduc- 
tion of  cryolite  by  sodium,  and  may  be  divided 
into  three  important  parts:  i.  The  production  of 
sodium.  2.  The  production  of  cryolite.  3.  The 
treatment  of  the  cryolite  with  sodium. 

Production  of  Sodium. — Netto  obtains  the  sodium 
professedly  in  a  very  economical  fashion,  by  allowing 
glowing  coke  to  act  upon  caustic  hydrate  of  soda. 
His  apparatus  (Fig.  i)  consists  of  a  cast-iron  retort, 
b,  which  is  filled  with  coke  and  charcoal  and  brought 
to  a  red  glow.  In  the  upper  part,  by  means  of  the 
mouthpiece  d,  the  caustic  hydrate  of  soda  is  intro- 
duced, which  is  melted  in  the  receptacle  e.  While 
the  caustic  hydrate  is  falling  drop  by  drop  upon  the 

*  Cf.  A.  Minet,  L' Aluminium,  pp.  132—137. 


PROCESSES.  9 

glowing  charcoal,  it  dissolves  almost  instantaneously. 
In  the  condenser  g  the  sodium-vapor  generated  is 
condensed. 

To  produce  100  kg  sodium  are  needed:  1000  kg 
NaOH,  120  kg  casting-pieces,  1200  kg  fuel,  reckoned 
as  coke,  and  150  kg  charcoal  as  reducing-agent. 


FIG.  i. 

Production  of  Cryolite.  —  Netto  uses  for  the  pro- 
duction of  this  substance  the  slag  which  results 
from  the  treatment  of  the  cryolite  with  sodium, 
and  which  essentially  consists  of  sodium  fluoride. 

If  one  mixes  sodium  fluoride  with  aluminum 
sulphate,  and  heats  the  mixture  to  the  melting- 
point,  there  results  the  following  reaction: 


the  sodium  sulphate,  which  is  formed  simultaneously 
with  the  cryolite,  is  separated  from  the  latter,  after 


io  PRODUCTION  OF  ALUMINUM. 

having  been  previously  cooled,  merely  by  lixivia- 
tion. 

Treatment  of  Cryolite  with  Sodium — For  the  suc- 
cess of  this  process  it  is  one  of  the  most  essential 
conditions  to  have  the  alkali-metal  affect  the  cryo- 
lite as  quickly  as  possible,  in  order  to  avoid  the 
excessive  loss  of  sodium  by  vaporization,  and  to 
prevent  too  strong  an  attack  upon  the  fire-bricks 
and  upon  the  natural  and  manufactured  fluorides 
always  found  in  association  with  silicates.  By 
means  of  a  number  of  very  ingenious  contrivances 
Netto  actually  succeeded  in  materially  shortening 
the  time  of  the  reaction.  Each  charge  gives  a 
product  of  about  5  kg  aluminum. 

Grabau  Process.*  —  In  order  to  prevent  the 
troublesome  consumption  of  the  fluoride,  Grabau 
treats  sodium  and  aluminum  fluoride  separately 
(producing  the  latter  himself),  and  allows  the  sub- 
stances to  react  on  each  other,  the  aluminum 
powdered,  the  sodium  in  the  form  of  small  cubes 
or  cylinders.  The  result,  with  the  simultaneous 
development  of  a  considerable  amount  of  heat,  is 
the  following  reaction: 

2A12F6  +  3Na2= A12 + Al2F6.6NaF. 

After  the  mass  has  been  cooled  down,  the  alumi- 
num is  found  as  a  regulus  on  the  bottom  of  the 

*D.  R.  P.  (Ger.  Pat.)  47031. 


PROCESSES.  II 

crucible,  covered  with  a  slag  of  cryolite,  which  dur- 
ing the  reaction  is  melted. 

Production  of  Aluminum  Fluoride.  —  Aluminum 
sulphate  and  cryolite  are  mixed  in  equivalent 
proportions;  heated,  the  following  reaction  takes 
place  : 


The  aluminum  fluoride,  since  it  is  insoluble  in 
water,  is  separated  from  sodium  sulphate  by  filtra- 
tion. 

Production  of  Sodium.  —  Grabau  obtains  sodium 
by  the  electrolysis  of  molten  sodium  chloride.  The 
principal  original  feature  in  his  process  is  the  form 
of  the  electrolytic  apparatus  (Fig.  2). 

The  double-walled  porcelain  receiver  BB  forms 
the  significant  feature  of  the  apparatus;  this 
receiver  enclos.es  the  negative  iron  electrode  n. 
The  current  enters  through  the  carbon  anodes  CC, 
flows  through  the  electrolytes  (melted  chloride  of 
sodium)  both  without  and  within  the  polar  cell 
BB,  and  makes  its  exit  at  n.  The  chlorine  passes 
out  at  d.  The  sodium,  since  it  is  lighter  than  its 
melted  chloride,  mounts  up  within  the  receiver  and 
escapes  through  the  tube  a,  whence  it  is  conducted 
into  the  condenser  M,  which,  filled  with  nitrogen 
or  hydrogen,  is  sunk  in  a  reservoir  5  containing 
petroleum.  The  screw  H  serves  to  remove  clogging 
material  which  may  eventually  collect  in  the  tube- 


12 


PRODUCTION  OP  ALUMINUM. 


shaped  portion  E  of  the  negative  electrode.  In 
addition  to  the  above-mentioned  process,  there  are 
still  other  well-known  processes  *  for  obtaining 
sodium  electrolytically,  such  as  those  of  Castner 


FIG.  2. 

(1890),    Minet    (1890),    Borchers  f    (1893),    Becker 
(1900). 

Frismuth  Process. — Aluminum-sodium  double  chlo- 
ride is  volatilized  in  the  retort,  in  a  chlorine 
current,  in  the  presence  of  common  salt;  upon  the 
chloride,  in  the  form  of  vapor,  sodium-vapor  in  a 

*  Cf.  A.  Minet,  Traite"  thSorique  et  pratique  d'e"lectrometal- 
lurgie,  p.  415  ff. 

f  Borchers,  Alkalimetalle,  in  Zeitschrift  fur  angewandte 
Chemie,  1893. 


PROCESSES.  13 

suitable  receptacle  is  allowed  to  act;  this  sodium- 
vapor  is  formed  in  a  peculiar  retort  from  a  mixture 
of  soda  and  carbon  heated  to  a  red  glow. 

Webster  Process.  —  This  is  based  upon  the  same 
principle  as  the  process  of  Deville.  The  original 
material  is  alum,  from  which  the  aluminum  chloride 
is  produced.  By  this  means  the  two  principal 
impurities  of  aluminum,  namely,  percentages  of 
iron  and  of  silicon,  are  avoided. 

The  Webster  process  was  utilized  by  the  Alu- 
minium Crown  Metal  Company  in  Holyhead,  at 
Birmingham. 

The  White  and  Thompson  Process.  —  This  operates 
similarly  to  that  of  Rose.  Three  parts  of  sodium 
and  four  parts  of  powdered  cryolite  heated  to  100° 
C.  are  mixed  in  a  sand-bath,  thoroughly  stirred  and 
allowed  to  cool.  .  To  this  are  added  four  parts  of 
aluminum  chloride,  and  the  whole  is  then  placed 
in  an  air-furnace,  heated  to  a  red  glow,  whereupon 
the  reduction  begins  immediately. 

Feldmann  Process  (Linden  vor  Hannover).  —  A 
mixture  of  aluminum-strontium  double  fluoride, 
strontium  chloride,  and  sodium  is  heated  to  the 
melting-point,  whereupon  the  following  reaction 
occurs  : 


Al2F6.3SrF2  +  3SrCl2  +  6Na  = 

2  Al  +  3SrF2  +  3SrCl2  +  6NaF. 

The    strontium  fluoride,   since  it  is  insoluble  in 
water,  can  be  separated  by  washing  it  away  from 


14  PRODUCTION  OF  ALUMINUM. 

the  other  constituents;  and  thus,  returning  into 
the  process,  it  serves  for  the  production  of  addi- 
tional quantities  of  the  .double  fluoride. 

b.  Processes  which  do  not  employ  Sodium. 

Under  this  heading  we  shall  speak  of  those 
methods  which  effect  the  reduction  of  aluminum 
without  the  aid  of  an  alkali-metal. 

Apart  from  the  Beketoff  process  (1865) — BeketofT 
proposes  magnesium  as  a  means  of  reduction — we 
may  here  mention: 

Reillon,  Montagne,  and  Bougerel  Process. —  This 
depends  on  a  reaction  the  correctness  of  which  has 
not  been  demonstrated:  the  production  of  alumi- 
num by  heating  a  mixture  of  clay,  carbon,  and 
bisulphide  of  carbon,  upon  which  a  hydrocarbon  is 
allowed  to  react. 

Baldwin  Process  (Chicago). — This  is  based  on  an 
insufficiently  defined  reaction,  which  in  my  opinion 
cannot  be  verified:  bauxite,  powdered  carbon,  and 
common  salt  are  so  to  react  upon  one  another 
under  the  influence  of  heat  that  an  aluminum-sodium 
compound  is  formed.  The  alloy  obtained  is 
furthermore  to  be  melted  with  a  quantity  of  sodium 
chloride,  and  thus  the  aluminum  is  to  be  separated 
from  the  alkali-metal. 

Faurie  Process. — A  quantity  of  sulphur,  carbon, 
and  clay  is  heated  to  a  red  glow.  First,  aluminum 
sulphide  and  bisulphide  of  carbon  will  be  formed, 
and  finally,  at  a  white  heat,  aluminum. 


PROCESSES.  15 

Stephen  and  Sanderson  Process. — The  details  of 
this  process  are  not  exactly  known.  On  the  one 
hand,  fluorhydric  acids  in  a  gaseous  state  are 
allowed  to  act  upon  a  quantity  of  alum  and  emery 
heated  to  a  red  glow  until  the  whole  mass  becomes 
of  a  pasty  consistency.  From  the  melt,  grains  of 
aluminum  containing  iron  are  deposited,  which 
may  be  purified  from  the  iron  by  dilute  sulphuric 
acid.  If  it  is  desired  to  obtain  an  alloy  of  aluminum 
and  iron,  hematite  is  added  to  the  melt. 

On  the  other  hand,  zinc  may  also  be  used  as  a 
reducing-agent,  which,  acting  in  the  form  of  vapor 
overshot  above  white-hot  aluminum  chloride,  is 
said  to  reduce  the  latter.  A  residuum  will  be  formed 
at  the  same  time,  containing  zinc  as  an  impurity ;  by 
heating  to  1100°  C.  this  zinc  may  be  gotten  rid  of. 

Pearson  and  Pratt  Process.  —  According  to  the 
proposal  of  these  engineers,  iron-aluminum  alloys 
are  obtained  in  blast-  or  cupola-furnaces  directly 
from  aluminum  ores.  The  latter,  with  this  end  in 
view,  are  mixed  with  iron  ores  as  rich  as  possible 
in  clay,  and  with  calcium  fluoride  (fluor-spar) — 
instead  of  common  lime — whereupon  the  mass  is 
introduced  into  the  blast-furnace. 

If  it  is  desired  to  produce  aluminum  steel,  the 
original  materials  must  be  free  from  sulphur  and 
phosphorus.  The  melt,  containing  aluminum,  is  then 
handled  by  the  Bessemer  process  in  the  usual  manner. 

The  place  of  the  lime  may  to  advantage  be 
wholly  taken  by  fluor-spar;  with  a  substitution  up 


16  PRODUCTION  OF  ALUMINUM. 

to  25%,  satisfactory  results  are  nevertheless 
achieved.  Thus,  for  example,  in  the  case  of  the 
ores  of  Staffordshire,  which  are  especially  rich  in 
protoxide  of  iron  and  alumina,  a  charge  has  the 
following  composition:  40  parts  clayey  ores,  n 
parts  lime,  4  parts  fluor-spar,  and  60  parts  carbon 
with  a  blast  of  hot  air;  an  equal  amount  of  coke 
with  the  blast  of  cold  air. 

Ste*fanite  Process. — This  patent  is  quite  similar 
to  the  one  just  described,  and  has  been  employed 
particularly  in  Germany.  It  consists  essentially  in 
adding  to  the  usual  blast-furnace  charge  emery 
or  alum  in  powder  or  briquette  form.  A  melt 
containing  aluminum  is  thus  obtained,  which, 
under  further  treatment  in  the  puddling-furnace, 
gives  a  metal  which  permits  of  being  hardened 
like  steel  and,  according  to  the  statement  made  in 
the  description  of  the  patent,  is  much  more  capable 
of  resistance  than  iron. 

Other  Processes. — For  the  sake  of  completeness 
we  add  still  other  processes  in  the  following  table, 
although  these  have  been  practically  tested  in  but 
few  instances. 

Process.  Proposed  Means  of  Reduction. 

Knowles  and  Corbelli Cyanogen  gas 

Gerhard  and  Fleury Hydrocarbon 

Morris  and  Chapelle Carbon 

Morris Carbonic  acid 

Lautherborn  and  Nieverth Iron 

Calvet  and  Johnson  Beuson Copper 

Dulls,  Basset,  and  Seymour Zinc 

Wilde Lead 

Weldon Manganese 


PROCESSES.  17 

The  original  material  in  the  case  of  all  these 
attempts  was  either  the  oxide  or  the  chloride  or 
fluoride  of  aluminum.  It  must  be  emphasized 
that  all  these  reductions  were  attempted  without 
the  assistance  of  electricity.  If,  therefore,  there 
has  been  no  practical  result  from  these  processes 
up  to  the  present  time,  as  we  have  already  stated, 
it  is  still  not  impossible  that  by  the  use  of  the 
electrical  current  in  this  connection  one  or  the 
other  of  these  processes  may  result  at  least  in  the 
formation  of  alloys  of  aluminum. 

B.  ELECTROCHEMICAL  METHODS  OF  ^PRODUCING 
ALUMINUM. 

The  processes  for  the  production  of  aluminum 
with  the  aid  of  the  electrical  current  may  be 
divided,  as,  indeed,  is  true  of  all  electrometallurgical 
methods,  into  two  groups:  the  electro  thermic  and 
the  electroty tic ;  to  these  may  be  added  those  pro- 
cesses in  which  both  functions  of  the  electric  current 

% 

are  simultaneously  active,  and  which  one  may  call 
combined  processes. 

Electro  thermic  Processes.  —  Electrothermic  pro- 
cesses are  those  in  which  the  current  plays  merely 
the  part  of  a  heating  agent,  regardless  of  whether 
the  calories  are  delivered  by  an  electric  arc  or  by 
a  resistance  with  a  current  flowing  through. 

In  the  first  case  the  electromotive  force  is  nearly 
that  of  the  usual  electric  arc,  amounting,  therefore, 


l8  PRODUCTION  OF  ALUMINUM. 

to  something  like  30  or  35  volts;  in  the  second 
case  the  tension  depends  upon  the  circumstances 
for  the  time  being.  The  resistance  material 
may  now  be  either  independent  of  the  reaction- 
substances  —  and  then  we  have  to  do  with  a  purely 
electrothermic  process—  or  the  reaction-substances 
are  themselves  the  ones  that  form  the  resistance,  and 
then,  under  certain  conditions,  the  electrothermic 
process  may  be  accompanied  by  an  electrolytic 
process  (the  combined  process). 

In  purely  electrothermic  processes  the  direct 
current  may  be  used  as  well  as  the  alternating. 

The  quantity  of  heat  Q  developed  by  the  current 
passing  through  may  be  calculated  by  the  formula 

Q=kEJtCal. 

E  signifies  the  difference  in  potential  in  volts  between 
the  point  of  entrance  and  the  point  of  exit  of  the 
current,  whereby  only  that  region  comes  under 
observation  which  by  virtue  of  its  slight  conduc- 
tivity produces  current  heat;  /  is  the  strength  of 
current  in  amperes,  t  the  time,  expressed  in  seconds  ; 
k  is  a  factor  of  proportion,  which  with  regard  to 
the  chosen  units  amounts  to  the  value  0.24.  We 
have,  then,  the  relation 


The  current-density,  that  is  to  say,  the  strength  of 
current  per  square  centimeter,  amounts  generally  to 
10  amp. 


PROCESSES.  19 

Electrolytic  Processes. — Here  the  current  operates 
in  twofold  fashion.  On  the  one  hand  it  develops 
heat  by  its  passage  through  the  electrolyte,  on 
the  other  hand  it  brings  about  the  electrolytic 
decomposition  of  the  electrolyte.  The  electrolyte 
is  then  found  to  be  in  a  liquid  state,  whether  as 
a  melt  or  as  a  solution.  It  goes  without  saying 
that  in  this  case  only  the  direct  current  may  be 
employed. 

The  weight  of  the  matter  separated  by  the  elec- 
trolysis is  proportional  to  the  amount  of  current, 
or,  at  a  given  time,  proportional  to  the  intensity 
of  current  /.  (Faraday's  law).  The  electromotive 
force,  which  in  the  case  of  soluble  anodes  amounts 
to  only  a  few  tenths  of  a  volt,  whereby  the  elec- 
trolytic process  confines  itself  merely  to  carrying 
the  element  in  question  from  one  electrode  to  the 
other,  in  the  case  of  insoluble  anodes,  and  there- 
fore in  the  case  of  a  decomposition  peculiarly 
electrolytic,  rarely  exceeds  5-6  volts. 

TJie  choice  of  current-intensity  at  the  cathode 
is  governed  by  the  particular  type  of  electrolysis, 
by  the  nature  of  the  metal  separated,  and  also 
by  the  temperature.  In  the  case  of  aqueous  solu- 
tions the  intensity  varies  between  o.ooi  and  0.01-0,02 
amp.,  in  the  case  of  molten  fluxes  between  0.5  and 
i  amp. 

Work  of  the  Current. — This  is  expressed  in  the 
formula 


20  PRODUCTION  OF  ALUMINUM. 

in  which  the  factors  E,  J,  and  t  have  the  same  mean- 
ing as  before. 

A  part  of  the  energy  is  converted  into  heat;   let 
Qi  be  this  portion;   we  then  have 


R  is  the  resistance  in  ohms  of  the  electrolyte. 

The  remainder  Q2  is  equivalent  to  the  energy- 
expenditure  of  the  chemical  process  taking  place 
in  the  electrolysis.  Its  value  is  expressed  by  the 
formula 


if  we  characterize  by  e  the  counter-electromotive 
force  of  the  decomposition. 
We  have  then 


or 

o.24EJt-o.24RJ2t+  0.248  ft. 

If  we  abbreviate  this  on  both  sides,  we  obtain 


an  expression  which  gives  us  the  principal  formula 
for  all  electrochemical  processes. 

Combined  Process.  —  Under  this  heading  should 
be  classified  all  reactions  in  which  an  electrothermic 
phenomenon  is  accompanied  and  converted  by  an 
electrolytic.  Let  us  suppose,  for  example,  that 
the  arc  serves  as  a  source  of  heat,  that  the  electrodes 


PROCESSES.  21 

are  at  the  beginning  of  the  process  independent 
of  the  materials  of  reaction,  and  that  the  electro- 
motive force  is  about  35  volts.  As  soon  as  the 
charge,  in  consequence  of  heating,  melts,  and  its 
volume  is  increased  by  filling  up,  thus  coming 
into  contact  with  the  electrodes,  the  electromotive 
force  may  sink  to  about  20  volts  or  even  lower, 
and  the  arc  disappears.  The  electrothermic 
phenomenon,  it  is  true,  still  remains  predominant, 
as*,  the  heat-effects  appearing  in  the  neighborhood 
of  the  electrode-surface  demonstrate;  on  the  other 
hand,  however,  there  takes  place  a  more  or  less 
well-defined  electrolytic  process,  which  in  the  case 
of  the  direct  current  diminishes,  in  the  case  of  the 
alternating  current  increases  the  product.  Simul- 
taneously the  current-density  gradually  falls;  this, 
in  the  case  of  a  purely  electrothermic  process, 
amounts  to  5-10  amp.  If  we  have  the  direct 
current,  then  the  phenomena  of  warmth  disappear 
forthwith,  the  difference  in  potential  and  the  current- 
density  approach  the  values  observed  universally 
in  the  case  of  salts  melted  by  electrolysis ;  in  brief, 
the  electrolytic  effect  of  the  current  predominates 
over  the  electrothermic,  which  latter  may,  indeed, 
finally  disappear  altogether. 

(a)    Electrothermic  Processes. 

Alumina  (A12O3)  is  reduced  by  means  of  carbon 

or  a  metal,  with  or  without  the  addition  of  a  flux. 

The  aluminum  produced  by  this  means  is  not 


22  PRODUCTION  OF  ALUMINUM. 

pure,  but  forms  according  to  the  method  of  the 
operation  an  alloy  (Cowles,  Heroult)  or  a  carbide 
(Moissan) . 

Moukton  Process. — The  application  of  the  electric 
current  to  the  reduction  of  alumina  by  means  of 
carbon  was  proposed  for  the  first  time  by  Moukton 
in  the  year  1862.  According  to  his  patent  the 
electric  current  is  to  be  conducted  through  a  reduc- 
tion-chamber charged  with  carbon  and  alumina, 
and  the  mixture  thus  brought  to  the  temperature 
requsite  for  the  reduction.  With  reason,  however, 
Borchers  emphasizes  the  fact  that  the  process 
mentioned,  even  had  Moukton  been  able  to  pro- 
duce a  metal  industrially  available,  would  not 
have  been  profitable;  for  not  until  long  after  the 
invention  of  the  dynamo-electric  machine  (1872) 
did  it  become  possible  to  maintain  electrical  energy 
inexpensively.  Apart  from  this,  however,  Moukton 
would  have  been  able,  according  to  his  patent,  to 
produce  merely  a  totally  useless  aluminum-carbide, 
and  by  no  means  a  metal  satisfying  the  demands 
of  industry. 

Cowles  Process. — Only  after  a  considerable  num- 
ber of  years,  during  which  the  application  of 
electricity  to  metallurgy  seemed  to  have  passed 
entirely  into  oblivion,  did  the  Cowles  brothers 
(1884)  come  forward  with  a  process  which  yielded, 
if  not  pure  aluminum,  at  least  alloys  containing 
aluminum  up  to  20%. 

The  characteristic  feature  of  this  Cowles  inven- 


PROCESSES.  23 

tion  is  the  utilization  of  a  type  of  apparatus  which 
is  styled  the  electric  furnace,  and  which  is  rightly 
considered  to  be  the  first  great  advance  in  electro- 
metallurgy. 

Electric  Furnaces.  —  It  is  true  that  there  were 
already  before  Cowles  apparatus  which  might 
be  enumerated  in  the  group  of  electrical  furnaces; 
still,  they  were  not  all  capable  of  being  utilized 
for  technical  purposes.  Such  were  the  furnaces  of 
Depretz  *  (1849),  Johnson  f  (1853),  and  Pichon  t 
(1853).  And  furthermore  the  operations  of 
Berthelot  (1862),  Siemens  §  (1879),  and  Louis  Clerc  ||. 
(1880)  did  not  advance  beyond  the  limits  of  labora- 
tory experiments. 

Although  the  Cowles  brothers  constructed  for 
the  first  time  a  practical  furnace,  in  which  con- 
siderable quantities  of  electrical  energy  were  con- 
verted, the  credit  of  having  anticipated  the  now 
perfected  apparatus  and  a  great  number  of  more 
recent  constructions  of  various  forms  belongs  to 
the  chemist  Heroult  and  to  those  who  showed 
how  to  produce  pure  aluminum. 

Cowles  Furnaces.  —  Eugene  and  Alfred  Cowles 
built  several  furnaces  for  specifically  electrothermic 
purposes,  that  is  to  say,  they  were  furnaces  in  which 

*  Compt.  rend,  de  1'academie  des  sciences,  Dec.  17,  1849. 

t  Engl.  Pat.   No.  700  of  1853. 

J  According  to  Andreoli,  Industrie,  1893. 

§  Engl.  Pat.  No.  2110  of  1879. 

||  Elektrotechn.  Zeitschr.,  1880. 


24  PRODUCTION  OF  ALUMINUM. 

the  reduction  of  metallic  oxides  by  chemical  means 
with  the  cooperation  of  the  current  heat  was 
carried  out. 

First  Type. — This  (Fig.  3)  is  the  subject  of  a  patent 
of  the  year  1885. 

The  material  with  which  the  furnace  is  to  be 
charged  is  introduced  in  minute  form,  mixed  with 
retort-carbon  in  fine  grains,  and  is  heated  to  a  white 
glow  by  the  heat  developed  by  the  passage  of  the 


FIG.  3. 

current.  The  furnace  was  originally  designed  for 
the  reduction  of  zinc  ores,  but  was  used  eventually 
for  other  ores  also,  in  particular  for  obtaining 
aluminum,  magnesium,  boron,  etc.  The  furnace 
is  built  with  a  retort  of  cylindrical  form,  which  is 
made  of  silica  or  some  other  current-insulating 
material.  It  is  surrounded  by  granulated  charcoal 
or  some  other  poor  conductor  of  heat,  and  is  shut 
off  on  the  one  end  by  a  plate  of  carbon,  which 
serves  as  positive  electrode,  on  the  other  end  by 
a  graphite  crucible,  which  provides  the  negative 


PROCESSES. 


25 


electrode.     The  latter  was  originally  also  designed 
to  be  a  condensing-chamber  for  the  zinc  vapors. 

Second  Type  (patented  in  the  year  1886). — This 
furnace  (Fig.  4),  which  is  based  on  the  same  principle 
as  the  previous  one,  has  the  form  of  a  parallel- 


FlG.  4. 

opipedal  chest  of  masonry.  The  two  bar-shaped 
carbon  electrodes  are  introduced  directly  into  the 
reaction-mixture,  which  rests  upon  a  support  of 
insulating  materials.  At  the  beginning  of  the 
operation  the  electrodes  are  made  to  approach  one 
another  until  there  is  an  opposite  contact;  the 
portions  of  the  furnace-charge  that  are  in  proximity 
to  the  ends  of  the  electrodes  forthwith  come  to  a 
white  heat,  whereupon  the  carbons  are  again 
slowly  separated  from  one  another  to  the  distance 
seen  in  the  design.  After  the  closing  of  the  current, 
immediately  after  the  separation  of  the  electrodes, 
the  distance  between  the  opposite  electrodes  amounts 
to  about  2  5  mm ;  the  distance  increases  to  1.2  m  at 
the  close  of  the  operation. 

Third  Type. — This  furnace,  which,   like  the  pre- 
ceding, was  patented  in  1886,  has  stood  the  test  of 


26 


PRODUCTION  OF  ALUMINUM. 


practical  experience  best  of  all  the  Cowles  appa- 
ratus; it  has  had  a  very  wide-spread  employment 
in  technology. 

The  furnace    (Figs.    5   and   6),   whose  walls  are 


FIG.  5. 

constructed  of  fire-brick,  has  an  average  height  of 
.66  m;  the  broad  side  is  1.68  m,  the  narrow  side 
0.51  m.  At  the  lower  edge  of  one  of  the  sides  is 


FIG.  6. 


an  opening  for  emptying  out  the  contents  of  the 
furnace  (comp.  Fig.  6).  In  both  side  walls  two 
cast-iron  tubes  are  set  in,  which  make  an  exten- 
sion of  the  carbon  bars  that  serve  as  electrodes. 


PROCESSES.  27 

Each  electrode  consists  of  nine  such  carbon  bars 
about  6  cm  in  diameter  and  80-97  cm  in  length. 
They  are  of  iron  or  copper  rod,  according  to  the 
alloy  which  is  to  be  produced;  the  rod  is  provided 
with  a  female  screw,  in  which  a  screw  is  inserted, 
by  means  of  which  the  electrodes  may  be  thrust 
into  the  cast-iron  tube. 

The  first  technical  tests  with  this  furnace  were 
carried  out  in  Cleveland  with  an  available  pressure 
of  50  volts  and  a  current-strength  of  1500  amp. 
The  power  (100  electric  horse-power)  was  furnished 
by  a  steam-engine. 

The  first  thing  was  to  produce  pure  aluminum. 
With  this  end  in  view,  the  reduction  of  the  alumina 
by  means  of  carbon  was  attempted;  but  these 
efforts  were  unsuccessful.  Conditions  became  more 
hopeful  when  the  place  of  carbon  was  taken  by 
a  metal,  iron  or  copper,  and  so,  without  difficulty, 
the  iron  and  copper  alloys  of  aluminum  were 
obtained. 

Later  the  Cowles  brothers  erected  a  factory  in 
Lockport,  where  there  was  water-power  at  their 
disposal  able  to  furnish  a  stream  of  3000  amp. 
and  50  volts  (200  horse-power).  In  Milton,  also, 
a  factory  was  started,  which  carried  on  the  industry 
by  the  method  described,  and  made  use  of  a  400- 
horse-power  dynamo-machine  for  generators,  the 
machine  at  60  volts  pressure  giving  a  current  of 
500  amp. 

As    material    for     producing    ferro-aluminum    a 


28  PRODUCTION  OF  ALUMINUM. 

mixture  of  bauxite,  iron  filings,  and  powdered 
carbon  may  be  used.  For  the  production  of 
copper-aluminum,  bauxite,  since  it  is  too  rich  in 
iron,  is  unsuitable.  Emery  or  corundum  is  used. 
In  addition,  it  is  needless  to  say,  copper  metal  takes 
the  place  of  the  iron  rod.  The  proportion  of  alumi- 
num varies  between  5  and  20%  in  ferro-alumi- 
num,  and  between  18  and  30%  in  copper-aluminum. 

The  costs  of  the  electrical  energy  per  kilogram 
of  finished  aluminum  were  in  Lockport  equivalent 
to  the  price  of  77  horse-power  hours;  that  is  to 
say,  a  horse-power  hour  gave  13  g  pure  aluminum 
or  65  g  20%  alloy.  In  Milton,  on  the  other  hand, 
in  round  numbers  40  horse-power  hours  were  neces- 
sary for  the  production  of  a  kilogram  of  aluminum; 
this  means  a  production  of  25  g  pure  aluminum 
or  125  g  20%  alloy  per  horse-power  hour. 

Fourth  Type  (Fig.  7). — This  possesses  a  great 
similarity  to  the  furnace  of  Johnson  of  the  year 
1853 ;  we  mention  it  here  for  the  sake  of  com- 
pleteness. The  details  may  be  seen  from  Fig.  7. 

He*roult  Processes. — The  experiments  of  Heroult, 
which  date  from  the  year  1886  and  which  are  not 
yet  concluded,  concern  themselves  with  almost 
every  department  of  electrometallurgy:  the  electro- 
thermic  production  of  aluminum  alloys,  of  silicon 
and  its  alloys,  of  calcium  carbide,  of  steel,  etc.,  and 
furthermore  the  production  of  pure  aluminum 
electrolytically. 

Of  these  various  processes,  which  are  described 


PROCESSES.  29 

in  a  great  number  of  patents,*  we  shall  single 
out  for  especial  mention  those  which  operate 
electro thermically ;  and  of  the  types  of  furnace 
constructed  by  Heroult  we  shall  mention  only  the 
more  important. 


FIG.  7. 

During  the  first  ten  years  of  his  investigations 
Heroult  constructed  practically  but  one  type  of 
furnace  —  that  which  the  French  to-day  style 
"cuve-cathode"  (crucible-cathode).  After  manifold 
modifications  in  the  design  originally  conceived, 

*  French  pat.  No.  170,003,  April  15,  1887. 
Belgian  77,100,  16, 

English         "       "  7,426,  May  21, 

German        "       "          4,165,  Dec.      8,    ' 
American     "       "      387,876,  Aug.    14,    " 


3°  PRODUCTION  OF  ALUMINUM. 

and  after  repeated  improvements,  he  finally 
brought  his  furnace  to  such  a  state  of  perfection 
that  its  technical  employment  is  at  present  very 
wide-spread. 

First  Type  of  Furnace  (Fig.  8). — It  reminds  one 


PIG.  8. 

of  the  furnace-construction  of  Siemens,   which  is 
represented  in  Fig.  9. 

We  must,  however,  lay  stress  upon  the  fact  that 
the  Heroult  furnace  from  a  technical  point  of  view 
marks  a  significant  advance;  it  is  built  more 
strongly  than  the  Siemens  furnace,  and  while  the 


PROCESSES. 


German  investigator  employed  his  furnace  merely 
for  laboratory  experiments  within  narrow  limits, 
namely,  for  the  electric  smelting  of  metals,  his 
apparatus  served  the  French  chemist  in  the  years 


FIG.  9. 


alloys, 


1886    and    1887    for    obtaining    aluminum 
in  particular  aluminum  bronze. 

In  his  patents  Heroult  characterizes  his  invention 
as  "a  process  for  the  production  of  aluminum  alloys 
with  the  aid  of  the  thermic  and  electrolytic  effect 
of  the  electric  current  upon  aluminum  oxide  (A12O3) 
and  the  metal  with  which  the  aluminum  is  to  be 
alloyed." 

In  order   to   keep   the    reduction-material   more 


32  PRODUCTION  OF  ALUMINUM. 

easily  in  a  molten  state,  and  so  accelerate  the  reduc- 
tion, Heroult  adds  also  a  few  parts  of  cryolite. 
Second   Type  of  Furnace. — For  the  first  experi- 


FIG.  10. 


ment,  which  was  carried  out  on  a  small  scale  only, 
the  furnace  just  described  answered  all  purposes, 
although  it  was  necessary  after  each  smelting  to 


PROCESSES.  33 

take  out  the  crucible  in  the  middle  of  the  furnace 
in  order  to  empty  it,  a  rather  troublesome  opera- 
tion, and  one  necessarily  entailing  a  loss  of  time. 

This  disadvantage  was  obviated  by  a  second 
form  of  construction  (Fig.  10),  in  which  the  finished 
product  at  definite  time-intervals  may  be  set  free 
through  a  tapping-hole  C. 

The  Schweizerische  Metallurgische  Gesellschaft, 
later  the  Aluminium-Industrie-Aktiengesellschaft, 
at  Neuhausen,  Switzerland,  undertook  to  operate 
this  furnace,  which  Heroult  had  described  in  his 
first  patent.  It  required  a  current  of  from  12  to 
15  volts  and  13,000  amp.  (200-250  horse-power), 
and  yielded  per  horse-power  hour  25-30  g  aluminum, 
which  was  obtained  in  the  form  of  a  copper  alloy 
containing  15-20  %  of  aluminum. 

Third  Type  of  Furnace. — In  the  year  1890  certain 
technical  journals*  published  the  description  of  a 
new  Heroult  furnace,  which  in  Neuhausen  and  in 
Froges,  France,  was  employed  especially  for  the 
electrolytic  production  of  aluminum.  From  Fig.  1 1 
it  may  be  seen  that  this  furnace  is  merely  a  modifi- 
cation of  the  preceding. 

Fourth  Type  of  Furnace. — This  was  constructed 
by  Heroult  in  collaboration  with  Kiliani,t  likewise 
for  obtaining  pure  aluminum  electrolytically.  It  is 
represented  in  Fig.  12. 

Its  characteristic  feature  consists  in  an  arrange- 

*  Industries,  VIII,  1890,  p.  499. 

t  D.  R.  P,  No.  50508,  April  21,  1889, 


34 


PRODUCTION   OF  ALUMINUM. 


ment  which  makes  possible  a  continuous  rotation 
of  the  positive  electrode,  and  which  clearly  sub- 
serves the  purpose  of  retarding  the  phenomena  of 
heat  such  as  are  often  observed  during  the  elec- 


FlG.    II. 


FIG.  12. 


trolysis  of  salts  at  the  fusing-point.  We  shall  see 
that  these  phenomena  occur  only  beyond  a  certain 
current-density,  and  that  they  become  fairly  rare 
when  one  is  working  with  several  apparatus  regu- 
lated for  pressure. 

Borchers  Furnaces.  —  Borchers  has  built  a  large 
number  of  furnaces,  some  for  the  reduction  of 
oxides  and  the  electrothermic  production  of  metal 
carbides,  and  some  for  the  electrolytic  production 
and  refining  of  certain  metals.  Since  most  of  them 


PROCESSES. 


35 


may  find  a  use  in  the  electrometallurgy  of  alumi- 
num, a  description  of  them  is  given. 

Electric  Furnaces  for  the  Production  of  the  Car- 
bides of  the  Earth-alkalies. — In  the  years  1880-89 
Borchers  succeeded,  by  means  of  carbon  at  a  high 


FIG.  13. 

temperature,  electrically  developed,  in  reducing 
all  the  metallic  oxides  till  then  regarded  as  unre- 
ducible ;  since,  however,  he  always  worked  with  an 
excess  of  carbon,  he  could  only  produce  carbides 


FIG.  14. 

which    contained    free    carbon.     Not    until    twelve 
years  later  d  d  the  French  chemists  Moissan  and 


30  PRODUCTION   OF  ALUMINUM. 

Bullier  succeed  in  obtaining  well-defined  carbides, 
which  were  free  from  carbon  in  excess. 

First  Type. — For  his  first  experiments  Borchers 
employed  an  apparatus  for  currents  of  12  volts 
and  120  amp.  (2  electric  horse-power).  Its  de- 
tails may  be  seen  in  Fig.  13.  It  may  readily  be 
constructed  with  fire-brick  and  bars  of  carbon. 

Between  two  carbon  bars  KK  40  mm  in  diam- 
eter, a  thinner  rod  of  carbon  k  only  4  mm  in 
diameter  and  40  mm  long  is  fastened.  Through 
a  suitable  arrangement  of  fire-brick  round  about  k 
a  cavity  is  left  free,  which  is  filled  with  a  mixture 
of  oxide  and  carbon.  Within  even  a  few  minutes 
after'  closing  the  circuit  the  whole  mass  between 
the  carbon  bars  KK  is  turned  into  carbide. 


FIG.  15. 

A  furnace  quite  similar  (Fig.  14)  was  employed 
in  1890  by  Acheson  for  producing  corundum  (silicon 
carbide) . 


PROCESSES.  37 

Second  Type. — The  arrangement  just  described 
is  also  practicable,  with  certain  modifications,  upon 
a  greater  scale.  Figs.  15  and  16  represent  the 
longitudinal  and  the  cross-section  of  a  furnace  built 


FIG.  16. 

for  currents  of  24  volts  and  610  amp.  (20  electric 
horse-power) . 

The  massive  carbon  bars  of  the  laboratory  fur- 
nace, Fig.  13,  are  here  replaced  by  carbon  plates  KK, 
between  which  three  small  carbon  bars  kkk,  4  mm 
in  diameter  and  80  mm  in  length,  are  introduced. 

Electric  Furnaces  for  the  Reduction  of  Metallic 
Oxides  by  means  of  Carbon.  —  For  this  purpose 
likewise,  having  in  view  the  production  of  pure 
metals  or  alloys,  Borchers  has  planned  certain  fur- 
naces, the  principal  types  of  which  we  will  now 
describe. 

First  Type. — This  finds  a  use  also  in  the  electro- 
metallurgy of  aluminum.  Between  two  large  car- 


38  PRODUCTION  OF  ALUMINUM. 

bon  bars  KK    (Fig.  17),  of   25-30  mm  diameter, 
a  thin  carbon  rod  W,  about  3  mm  in  diameter  and 


FIG.  17. 

45  mm  long,  is  fastened.  This  lies  in  the  axis  of 
a  small  paper  cartridge,  about  40  mm  in  length, 
which  is  filled  with  a  mixture  of  clay  and  carbon. 
After  the  cartridge  has  been  covered  over  with 
coarse  carbon  powder  the  circuit  is  closed  (current 
about  35-40  amp.).  The  reduction  is  complete  at 
the  expiration  of  three  to  four  minutes.  After 
cooling  down,  the  carbon  rod  W  is  found  to  be 
surrounded  by  a  mass  which  consists  of  aluminum 
rich  in  carbon. 

If  copper  or  copper  oxide  is  added  to  the  fur- 
nace-charge, one  obtains,  instead  of  a  metal  con- 
taining more  or  less  carbon,  a  copper-aluminum 
alloy. 

The  current-strength  specified  expresses  a  cur- 
rent-density of  500-600  amp.  per  square  centimetre 
of  cross-section,  measured  at  the  middle  copper  rod 
W\  if  the  current-density  be  increased  to  1000  amp., 


PROCESSES.  39 

it  is  possible  to  melt  with  the  apparatus  even  the 
most  refractory  metals. 

The  pressure  required  for  a  current-density  of 
500-600  amp.  amounts  to  10-17  volts. 

Chronologically,  these  investigations  of  Borchers — 
and  this  we  are  not  willing  to  pass  over  without 
mention — are  three  or  four  years  later  than  the 
experiments,  already  described,  of  Cowles  and 
Heroult. 

Second  Type. — Fig.  18  shows  one  of  the  simplest 
forms  of  the  Borchers  fur- 
nace. The  graphite  crucible 
T  contains  the  mixture  0  of 
oxide  and  carbon  which  is  to 
be  reduced,  and  represents  at 
the  same  time  one  of  the 
two  electrodes,  whilst  the 
other  is  formed  by  the  mas- 
sive carbon  bar  K.  Between 
the  two  the  thin  carbon  rod 
W  is  introduced.  5  is  a  fire-brick  covering  for  the 
crucible. 

Third  Type. — Two  further  forms  of  technical 
apparatus  *  are  represented  in  the  three  following 
illustrations.  One  (Figs.  19  and  20)  rests  on  a 
plate  F,  which  is  provided  with  two  backs,  of 
which  the  one  (B)  is  fastened  to  the  foot-plate, 
or  is  cast  in  the  same  piece  with  it,  while  the  other 

*  Borchers,  Proben,  in  Zeitschrift  fur  angewandte  Chemie. 
1892,  p.  133 


PRODUCTION  OF  ALUMINUM. 
K 


Fig.  20. 


FIG.  21. 


PROCESSES.  41 

(S),  through  the  iron  band  Z,  by  means  of  a  screw 
or  spring,  may  be  made  to  approach  the  back  B. 
To  both  backs  a  contrivance  is  attached  for  the 
purpose  of  receiving  the  iron  plate  G.  This  arrange- 
ment serves  on  the  one  hand  to  support  the  cru- 
cible 7,  on  the  other  hand  to  guide  securely  the 
back  5  as  it  approaches  B. 

If  necessary,  that  is  to  say,  if  the  crucible  is 
no  longer  sufficiently  high,  a  fire-brick  or  asbestos 
plate  is  placed  beneath.  The  remaining  portions 
of  the  apparatus,  as  well  as  the  fire-brick  covering 
c,  the  carbon  bars  K  and  k,  the  carbon-container  z, 
are  similar  to  the  corresponding  parts  of  the  fur- 
nace last  described. 

Another  and  a  very  simple  form  of  crucible- 
holder  is  seen  in  Fig.  21.  It  serves  to  hold  firmly 
crucibles  of  various  diameters. 

Upon  an  essentially  different  principle,  namely, 
the  electrolysis  of  melted  aluminum  compounds, 
is  based  a  furnace  which  is  represented  in  Fig.,  22, 
and  which  was  constructed  by  Borchers  especially 
for  the  electrometallurgical  production  of  aluminum. 

T  is  a  crucible  with  fire-brick  bottom  B,  the 
interior  of  which  is  entirely  lined  with  a  mantle  F 
of  alumina  or  some  other  refractory  aluminum 
compound.  In  the  floor-lining  a  steel  plate  K 
is  inlaid,  into  which  the  copper  tube  R  is  screwed ; 
this  tube  may  be  cooled  by  water  or  by  some  other 
suitable  means.  The  cold  water  is  introduced 
through  a  narrow  tube  E,  while  the  warm  escapes 


42  PRODUCTION  OF  ALUMINUM. 

through  the  tube  X,  which  reaches  almost  to  the 
upper  end  of  the  copper  tube  R.  •  The  latter, 
through  the  rivet  V  and  the  cable  N,  is  connected 


with  the  generator,  and  is  thus  the  means  of  con- 
ducting the  current  to  the  steel  plate  K,  which  at 
the  beginning  of  the  operation  serves  as  cathode. 
The  anode  is  the  massive  carbon  bar. 


PROCESSES.  43 

Apparatus  of  Botchers'  construction  were  built  by 
the  firm  of  E.  Leybold's  Successor  in  Cologne,  in 
a  form  convenient  for  experiments,  for  currents  of 
120-200  amp.  and  5-12  volts. 

Of  the  furnace  types  mentioned,  the  last  has  been 
tested  with  especial  thoroughness;  we  should, 
however,  remark  that  the  Heroult  and  the  Minet 
crucible-cathode  furnaces  preceded  it,  which,  more- 
over, operate  with  currents  of  6000  amp.  and 
8  volts  (65  electric  horse-power),  when  used  in  the 
electrometallurgy  of  aluminum,  and  with  a  like 
strength  of  current  require  32  volts  (260  electric 
horse-power)  when  used  for  the  production  of 
calcium  carbide. 

Willson  Process.* — The  first  furnace  which  was 
constructed  by  the  American  engineer  Willson 
for  the  electric  preparation  of  aluminum  com- 
pounds (Fig.  23)  reminds  one  of  the  apparatus  of 
Heroult  and  Borchers.  His  process  is  based  on 
the  reduction  of  alumina  by  the  electric  arc.  Later 
Willson  devised  still  another  arrangement  (Fig.  24) 
which  originated  in  the  idea  of  saving  as  much  as 
possible  the  wear  and  tear  upon  the  anodes  in  the 
electric  furnaces  which  operate  according  to  the 
combined  electrothermic-electrolytic  process.  To 
this  end  he  gave  the  carbon  anode  the  form  of  a 

*  American  pat.  No.  430453,  June  17,  1890. 
"  492377.  Febr.  21,  1893. 
English    "   "    4757,  1891. 
"   21696,  1892. 
"   "   21707,  1892. 


44 


PRODUCTION  OF  ALUMINUM. 


tube,  into  which  he  introduced  hydrogen,  coal-gas, 
or  a  chosen  hydrocarbon.  The  apparatus  served 
principally  for  making  aluminum  bronze  from  cop- 
per and  corundum. 


FIG.  23. 

It  is  worthy  of  remark  that  the  idea  which  is 
the  basis  of  the  Willson  process — an  idea  dating 
from  the  year  1890 — had  been  already  developed 
by  Minet  in  a  patent  of  1887,  to  which  we  shall 
return  for  a  more  detailed  consideration  later. 

At  about  the  same  time  Willson  also  constructed 
a  calcium-carbide  furnace,  which,  however,  like 


PROCESSES. 


45 


the  Borchers  furnace,  was  available  merely  for  the 
production  of  carbide  with  an  excess  of  carbon. 


Moissan's  Researches.  —  The  attempts  to  reduce 
alumina  in  the  electric  furnace  by  means  of  carbon, 
which  had  been  relinquished  by  Cowles,  were 
resumed  in  the  year  1892  by  Moissan.  He  suc- 
ceeded in  producing  at  a  high  temperature  an 
aluminum  carbide,  expressed  in  the  formula  CsAU. 
Besides  this,  we  owe  to  the  labors  of  Moissan  a 
great  number  of  well-defined  metal  carbides,  in 
particular  the  calcium  carbide,  which  he  produced 
in  collaboration  with  Bullier.  Moissan  availed 
himself  in  its  manufacture  of  a  furnace  which 
Fig.  25  shows  in  cross-section,  and  Fig.  26  in  com- 
plete view. 


46 


OP  ALVM1NVM. 


The  characteristic  feature  of  this  furnace,  which 
was  constructed  in  the  year  1892  and  exerimentally 


FIG.  25. 

tested  in  the  "Conservatoire  des  arts  et  metiers," 
are,    according   to    Moissan's   own   statement,    the 


FIG.  26. 


perfect  separation  of  the  electric  and  the  thermic 
effects  of  the  current,  and  the  localizing  of  the 
developed  heat  to  a  space  closed  in  on  all  sides. 


PROCESSES. 


47 


The  author,  in  the  year  1891,  built  a  furnace  of 
a  very  similar  type  (Fig.  27),  and,  indeed,  in  the 


FIG.  27. 

same  laboratory  with  Moissan.  Only  the  arrange- 
ment of  the  electrodes  is  different;  in  the  case  of 
the  Moissan  furnace  they  lie  horizontally,  while 
with  Minet  they  may  be  fastened  in  any  desired 
position  by  means  of  a  special  device. 

Menges  Process.*  —  This  process  makes  use  of 
the  electric  arc  itself  for  the  production  of  aluminum. 
Fig.  28  gives  the  entire  view  of  the  apparatus,  as 
in  use  in  1886. 

It  resembles  quite  closely  an  arc  lamp  whose 
lower  electrode  is  firmly  fastened  in  the  bottom  of 
a  crucible  of  good  conducting  material.  The  upper 
electrode  pierces  the  lid  of  the  crucible,  and  is  kept 
by  means  of  a  mechanical  arrangement  at  a  con- 
venient distance  from  the  lower  electrode.  It 

*  D.  R.  P.  No.  40354,  1886. 


48  PRODUCTION  OF  ALUMINUM. 

consists  of  a  mixture  of  carbon,  as  a  good  conduct- 
ing material,  and  the  oxide  to  be  reduced.  The 
entire  apparatus  may  be  surrounded  by  a  thick 
enveloping  mantle,  so  that  the  melt  may  be  under- 
taken under  pressure  as  well.  The  process,  how- 
ever, has  had  no  technical  use. 

Kleiner-Fiertz  Process.*  (1886). — This  resembles, 
in  general  design,  the  Menges  patent,  except  that 
it  has  special  reference  to  the  melting  of  cryolite. 
The  electrodes  reach  into  a  vessel  filled  with  cryolite, 
which  has  an  inner  lining  of  bauxite  and  clay  (Figs. 
29  and  30).  Both  are  movable,  but  while  the 
lower  is  to  be  adjusted  by  hand  only,  the  movement 
of  the  upper  electrode  is  governed  automatically 
by  means  of  a  lever  and  a  solenoid.  The  vibrations 
of  the  lever  are  deadened  and  limited  by  a  piston, 
which,  applied  to  the  apparatus  from  above,  dips 
into  a  speedily  filled  cylinder. 

In  consequence  of  its  expensive  mode  of  opera- 
tion, the  Kleiner-Fiertz  furnace  has  been  but  little 
used. 

Brin  Brothers'  Process  (1888). — With  this  process 
it  is  possible,  by  means  of  a  special  device,  to  intro- 
duce into  the  arc  light  an  indifferent  gas,  and 
so  to  have  the  reaction  take  place  in  an  inactive 
atmosphere.  The  furnace  pressure  varies  between 
50  and  100  volts  on  the  one  hand,  and  between 
20  and  25  volts  on  the  other  hand,  and  is  governed 
according  to  the  method  by  which  the  aluminum 

*  D.  R.  P.  No.  42022,  1886. 


PROCESSES. 


49 


is  reduced.  The  brothers  Brin  propose  two  different 
methods.  In  either  event,  the  original  composition 
is  the  same;  it  consists  of  100  parts  of  bauxite, 
125  parts  of  common  salt,  and  a  certain  quantity 
of  borax. 


FIG.  28. 


FIG.  29. 


FIG.  30. 


The  first  method  operates  exclusively  electro- 
thermically.  The  specified  materials  are  melted  in 
a  closed  crucible  until  white  fumes  appear;  the 
negative  carbon  electrode  is  then  immersed  in  the 
mixture,  while  the  positive  remains  at  the  surface 
of  the  bath.  Under  these  conditions  the  arc  works 
at  a  pressure  of  50-100  volts.  The  aluminum 
is  separated  at  the  negative  electrode;  according 


5° 


PRODUCTION  OF  ALUMINUM. 


to  the  statement  of  the  inventor,  it  would  be  mainly 
dispersed  and  lost,  were  the  metal  not  protected 
from  oxidation  by  a  current  of  carbonic  acid,  which 
immediately  conducts  the  fumes  into  the  con- 
densing-chamber. 

In  the  second  and  electrolytic  method,  both 
carbon  electrodes  are  dipped  into  the  bath.  At 
the  positive  pole  chlorine  is  formed,  from  chloride 
of  sodium;  at  the  negative  electrode  sodium  and 
aluminum  are  separated,  the  latter  indirectly  in 
consequence  of  the  reduction  of  the  alumina  by 
sodium.  Both  metals  are  assembled  on  the  bottom 
of  the  crucible  in  the  form  of  an  alloy  rich  in  alumi- 
num. 

Bessemer  Process.    (Fig.  31). — The  Bessemer  fur- 


FIG.  31. 

nace  consists  of  three  parts:  the  heating-chamber 
A,  the  reduction-chamber  B,  and  the  condenser  C. 
The  heating-chamber  A,  of  sheet  iron,  is  filled 
with  fire-brick,  like  the  Siemens  generators,  and 
is  calculated  for  a  pressure  of  four  atmospheres; 
at  a  the  flame-gases,  mixed  with  air,  are  introduced, 
while  the  products  of  combustion  escape  through 
the  chimney  at  x. 


PROCESSES.  51 

When  the  bricks  are  brought  to  a  red  glow,  the 
openings  a  and  x  are  closed,  and  heating-gases 
are  introduced  through  the  tube  b  into  the  pre- 
viously warmed  reduction-chamber  B;  these  gases, 
under  the  effect  of  a  hot-air  current  which  comes 
from  A,  and  in  consequence  of  the  high  pressure 
that  prevails  in  B,  are  consumed  at  a  very  high 
temperature.  When  by  this  means  the  tempera- 
ture desired  in  B — a  red  glow — has  been  obtained, 
the  charge  is  introduced,  which  consists  of  a  com- 
position of  powdered  aluminum  ore  and  carbon 
pressed  into  briquette  form,  to  which  as  a  flux  soda, 
chalk,  or  borax  is  added.  The  whole  is  brought 
in  the  electric  arc  to  a  very  high  temperature,  and 
thus  the  reduction  of  the  alumina  by  carbon  is 
effected.  The  aluminum-vapors  arising  are,  with 
a  simultaneous  slackening  of  the  gaseous  tension, 
conducted  to  atmospheric  presure  in  the  condenser 
C,  which  is  cooled  with  water. 

Fanner  Process.  —  Farmer  produces  pure  alumi- 
num directly  in  the  electric  arc,  creating  the  arc 
within  an  electric  crucible  between  two  rods  10-15 
mm  in  diameter.  The  rods  consist  half  of  carbon, 
half  of  corundum  or  emery,  and  are  luted  by  means 
of  sugar  or  petroleum  residua.  Into  the  crucible, 
through  the  tube  E,  air,  coal-gas,  petroleum- 
vapor,  water-vapor,  or  zinc -vapor  is  introduced, 
whereby,  according  to  the  statement  of  the  inventor, 
the  reduction  is  accelerated;  futhermore,  it  is  said, 
the  temperature  of  the  crucible  is  heightened  there- 


52  PRODUCTION  OF  ALUMINUM. 

by,   and  the  dissociation  introduced  at  the  right 
moment. 

K  is  a  solenoid,  which  is  applied  to  the  principal 
circuit  by  means  of  a  shunt,  and  is  for  the  pur- 
pose of  holding  the  arc  firmly  in  the  middle  of  the 
crucible.  As  soon  as  its  resistance  increases,  the 
power  of  attraction  of  the  magnetic  coil  K  over- 
comes the  elastic  force  of  the  spring  k,  the  arma- 
ture /  sinks  in  consequence  at  i  and,  by  means  of 
a  special  contrivance  seen  in  the  drawing,  causes 
the  electrode  carbons  to  approach  each  other. 

A 


FIG.  32. 

If  the  circuit-breaker  L  is  set  up  in  front  of  the 
crucible  A,  there  is  thus  afforded  a  possibility  of 
cutting  out  the  corresponding  crucible  at  the  con- 
clusion of  the  reaction,  and  so  of  keeping  up  the 
operation  continuously. 

The  gases  of  reduction  escape  through  the  out- 
let C',  while  through  the  furnace-channel  C  what  is, 
according  to  the  statement  of  the  patentee,  almost 
chemically  pure  aluminum  flows  off. 


PROCESSES. 


53 


The  process  is  as  adaptable  to  the  direct  as  to 
the  alternating  current. 

Gerard-Lescuyer  Process.* — Fig.  33  gives  the  de- 
tails of  the  furnace,  which  recalls  one  of  the  John- 
son constructions.  An  arc  is  produced  between 


FIG.  33. 

two  easily  exchangeable  electrodes,  which  consist 
of  a  composition  of  50  parts  of  dried  alumina, 
80  parts  of  carbon  powder,  and  100  parts  of  copper- 
dust,  and  are  pressed  into  rods  by  the  addition  of 
tar  or  pitch.  An  endless  screw  makes  possible 
the  moving  forward  (in  plain  sight)  of  the  electrodes, 
according  to  the  amount  of  wear  and  tear. 

The  aluminum  bronze  formed  falls  on  the  bot- 
tom of  a  flame-furnace,  and  here  comes  into  con- 
tact with  lime,  which  accelerates  the  melt.  The 
bottom  is  partially  heated  through  the  combustion 


*  D.  R.  P.  No.  48040,  1887. 


54 


PRODUCTION  OF  ALUMINUM. 


of  carbon  dioxide,  which  is  conducted  to  the  arc 
at  G. 

The  metallic  mass  thus  obtained,  which  con- 
tains about  20%  aluminum,  forms  the  point  of 
departure  for  the  production  of  pure  aluminum; 
it  is  diminished  and  serves  in  the  place  of  copper 
as  an  element  of  new  electrodes.  After  repeated 
operations  of  this  sort,  by  a  continued  process  of 
enrichment,  one  finally  succeeds  in  obtaining  a 
metal  almost  pure. 


FIG.  34. 

The  Furnace  of  the  Electric  Construction  Corpora- 
tion *  (Fig.  34)  makes  possible  the  heating  of 
the  charge  by  an  arc  or  by  a  resistance  interposed 

*  D.  R.  P.  No.  55700,  1890. 


PROCESSES. 


55 


between  the  electrodes.  The  charge  itself  may 
also,  of  course,  serve  as  such  resistance. 

In  Fig.  34  F  is  the  furnace-pit  with  the  charging- 
funnel  a,  which  latter  is  provided  with  two  slides 
A  A,  intended  to  prevent  the  entrance  of  air  during 
the  charging.  On  both  sides  of  the  smelt  ing- 
furnace  are  the  electrodes  c'c'\  these  usually  con- 
sist of  carbon  cylinders,  which  are  enclosed  in 
metal  shells  cc.  c"c"  are  thin  rods  of  carbon  or 
metal  which  serve  for  heating  when  the  circuit 
is  closed.  The  gases  and  vapors  developed  pass 
off  through  the  upper  part  of  the  furnace  at  g, 
while  the  slag  is  drawn  off  at  h:  xoc  are  doors 
closed  by  means  of  clay  plugs  or  clay  mortar. 

This  furnace  of  the   Electric   Construction  Cor- 


FIG.  35. 

poration  has  been  widely  used  in  the  production  of 
aluminum  by  the  electrothermic  method. 


5<$  PRODUCTION-  OF  ALUMINUM. 

Schneller  and  Astfalck  Process  (1890).  —  The 
temperature  necessary  for  the  reduction  of  the 
alumina  is  here  developed  by  means  of  an  alterna- 
ting current  transformed  at  a  high  tension  (Fig.  35). 
The  high  tension  is  necessary  because  of  the  poor 
conductivity  of  the  materials  to  be  reduced.  Simul- 
taneously, and  for  the  like  reason,  the  wide  upper 
surface  which  is  exposed  to  the  reducing-gases  is 
used  to  advantage.  For  reducing-gases  hydrogen 
or  a  convenient  hydrocarbon  is  employed.  The 
furnace-charge  itself  consists  of  alumina,  aluminum 
sulphide,  chloride,  or  fluoride. 

(b)   Electrolytic  Processes  for  the  Production  of 
Aluminum. 

In  order  to  be  able  to  subject  a  compound  to 
electrolysis,  it  must  first  be  converted  into  the 
fluid  state  of  aggregation ;  this  may  occur  through 
dissolving  or  melting.  If  the  substance  concerned 
contains  water  in  chemical  association,  it  might 
also  be  made  fluid  by  melting  in  its  water  of  crystal- 
lization or  hydrate-water;  however,  for  aluminum 
we  have  no  examples  of  this  kind.  As  for  the 
separation  of  aluminum  from  the  aqueous  solu- 
tions of  its  salts,  there  are  extant,  indeed,  several 
projects  having  this  end  in  view.  Yet,  since  they 
are  all  impracticable,  we  shall  limit  ourselves  in 
the  following  pages  to  a  brief  description  for  the 
sake  of  completeness.  The  only  electrolytic  proc- 


PROCESS £S.  5? 

esses  which  have  found  a  practical  technical  appli- 
cation depend  upon  the  electrolysis  of  aluminum 
compounds  in  the  molten  condition. 

The  Electrolysis  of  Dissolved  Aluminum  Salts.— 
This  subject  has  been  thoroughly  treated  by 
Borchers  in  his  Electrometallurgy;*  we  give  here  a 
brief  extract. 

It  is  a  fact  experimentally  verified  that  the 
electrolysis  of  aluminum  salts  in  aqueous  solution 
or  in  some  other  medium  of  solution  containing 
hydrogen  and  oxygen,  in  consequence  of  the  great 
affinity  of  the  aluminum  for  oxygen  in  the  nascent 
state,  always  gives  the  hydroxide,  and  never  the 
metal;  nevertheless  some  inventors  have  asserted 
that  under  certain  conditions  they  have  obtained 
metallic  aluminum  through  the  electrolysis  of  its 
dissolved  compounds. 

The  oldest  assertions  of  this  sort  are  found  in 
the  English  patent  of  Thomes  and  Tilly,  f  who 
electrolyze  an  aqueous  solution  of  aluminum  hy- 
droxide freshly  precipitated  in  cyanide  of  potassium, 
and  in  the  patent  of  Corbelli,J  who  recommends 
the  following  electrolytes:  2  parts  aluminum  sul- 
phate or  alum,  dissolved  with  i  part  calcium  or 
sodium  chloride  in  7  parts  water.  The  anode  is 
to  be  quicksilver,  the  cathode  zinc. 

*  Borchers,  Elektrometallurgie,  Verlag  von  H.  Bruhn, 
Braunschweig,  1896,  p.  108  ff. 

f  Engl.  Pat.  No.  2756,  1855.  According  to  J.  W.  Richards, 
Aluminum,  26.  Edition,  London,  1890. 

J  Eng.  Pat.  No.  507,   1858.     J.  W.  Richards,  loc.  cit. 


5^  PRODUCTION  OP  ALUMINUM. 

Dingler's  Journal,  in  Part  I  for  August  1854, 
contains  an  account  of  an  "alleged"  process  for 
plating  copper  galvanically  with  aluminum  or 
silicon.  In  order  to  obtain  aluminum,  a  solution 
of  hydrate  of  alumina  in  hydrochloric  acid  is  made ; 
into  the  solution  is  introduced  a  porous  vessel  of 
clay,  which  contains  an  amalgamation  of  zinc  plate 
and  sulphuric  acid  in  the  proportion  of  i  to  12. 
The  zinc  plate  is  connected  by  a  copper  wire  with 
a  copper  plate  of  the  same  dimensions  which  is 
likewise  immersed  in  the  solution  of  alumina. 
After  a  few  hours  the  copper  plate  should  be  covered 
with  a  thin  incrustation  of  aluminum,  which,  it 
is  stated,  has  the  color  of  lead,  becomes,  on  polish- 
ing, bright  like  platinum,  and  is  tarnished  neither 
in  air  nor  in  water.  This  metallic  covering,  it  is 
alleged,  is  also  precipitated  from  solutions  of  alum 
and  aluminum  acetate. 

In  a  very  similar  apparatus  silicon  also  is  separated 
from  an  electrolyte  which  is  produced  by  melting 
together  i "  part  silica  with  2 . 5  parts  sodium  car- 
bonate and  dissolving  the  melt  in  water.  If  in 
addition  a  pair  of  Smee  elements  are  connected 
with  the  circuit,  the  separation  of  the  silicon  very 
soon  follows,  and  in  fact,  as  the  patentee,  George 
Gore*  of  Birmingham,  maintains,  in  the  form  of 
a  silver-white  incrustation. 

J.   Nickles  f  'is  of   the  opinion  that  in  the  pro- 

*  Philosophical  Magazine,  March  1854,  p.  227. 
t  Journal  de  Pharmacie,  June  1854,  p.  476. 


PROCESSES.  59 

cesses  just  described  an  electrolytic  result  might 
clearly  have  been  observed ;  that  the  precipitation, 
however,  was  by  no  means  of  aluminum,  but  rather 
zinc,  which  could  have  originated  from  the  zinc 
sulphate  contained  in  the  porous  cell. 

Jeanson,*  at  a  temperature  of  60°  C.,  electrolyzes 
aluminum  salt  solutions  having  a  specific  weight 
1.15-1.16. 

Haurd  f  recommends  an  aqueous  solution  of 
cryolite  (?)  in  magnesium  chlorides  or  manganese 
chlorides. 

Bertram  J  asserts  that  he  has  precipitated  the 
metal  from  solutions  of  aluminum  and  ammonium 
fluoride. 

J.  Braun  §  (Berlin)  affirms  that  he  has  produced 
aluminum  at  an  ordinary  temperature,  by  elec- 
trolysis of  an  alum  solution,  having  a  specific  weight 
of  1.03-1.07. 

According  to  an  English  patent  of  Overbeck  and 
Niewerth,  ||  an  aqueous  solution  of  the  salts  of 
aluminum  with  organic  acids  is  electrolyzed ;  or 
else,  of  compounds  which  form  similar  salts;  or, 
finally,  of  aluminum  sulphate  in  combination  with 
other  metal  chlorides. 

Senet^f  claims  credit    for  a.  process    similar   to 

*  Annual  Record  of  Science  and  Industry,  1875.  From  J.  W. 
Richards,  Aluminum,  26.  Ed.f  London,  1890. 

t  U.  S.  A.  P.  No.  228900,  June  15,  1880.      Richards,  loc.  cit. 

J  Compt.  rend.,  Bd.  LXXXIII,  1876,  p.  854. 

§  D.  R.  P.  No.  28760. 

||Engl.  Pat.  No.  5756,  1883;    J.  W.  Richards,  loc.  cit 

1[  Cosmos  les.mondes,  1885;    Richards,  loc,  cit. 


60  PRODUCTION  OF  ALUMINUM. 

the  preceding;    he  employs  only  currents  of  6-7 
volts  and  4  amp. 

Walter  *  electrolyzes  a  solution  of  aluminum  ni- 
trate, using  a  platinized  copper  plate  as  electrode. 

Reinbold  f  recommends  the  following  electro- 
lytes for  the  production  of  aluminum  incrusta- 
tions upon  other  metals:  50  parts  alum  are  dis- 
solved in  300  parts  water,  mixed  with  10  parts 
aluminum  chloride  and  heated  to  93°  C. ;  after  the 
cooling  down  39  parts  cyanide  of  potassium  are 
added  to  the  solution. 

R.  de  Montgelas  J  first  precipitates  from  a  solution 
of  aluminum  chloride  containing  iron  electrolytic 
iron,  and  then,  after  the  addition  of  lead  oxide, 
zinc  oxide,  or  tin  oxide,  separates  the  aluminum 
simultaneously  with  the  metal  of  the  added  oxide. 

By  the  process  of  Falk  and  Schaag  §  salts  of 
aluminum  are  mixed  with  non-volatile  organic 
acids  in  aqueous  solution  with  the  cyanides  of  cop- 
per, gold,  silver,  tin,  or  zinc;  the  conductivity  of 
the  bath  thus  obtained  is  increased  by  the  addi- 
tion of  an  alkali  nitrate  or  alkali  phosphate,  and 
the  resulting  alloy  then  separated  under  the  influ- 
ence of  the  current. 

Burghardt  and  Twining  electrolyze  aqueous  solu- 
tions of  alkali  aluminates,  to  which  cyanides  and 


*  D.  R.  P.  No.  40626. 
I  Jewellers'  Journal,  1887. 
%  Engl.  Pat.  No.  10607,  1886. 
§  R.  D.  P.  No.  48078. 


PROCESSES.  6 1 

eventually  also  other  compounds  of  metal  oxides 
and  alkalis  are  added.  At  a  temperature  of  80°  C., 
according  to  the  statement  of  the  patentee,  alumi- 
num or  one  of  its  alloys  is  precipitated. 

According  to  Nansen  and  Pfleger,*  in  contrast  to 
the  previous  processes,  the  cooling  down  of  the 
electrolyte  as  far  as  to  40°  C.  directly  promotes 
the  separation  of  pure  aluminum  or  its  alloy  with 
magnesium. 

According  to  Rietz  and  Herold,f  aluminum  is 
precipitated  from  a  solution  containing  aluminum, 
starch,  and  dextrose,  which  is  electrolyzed  between 
platinum  electrodes  of  great  current-densities;  the 
aluminum  being,  of  course,  of  a  spongy  consistency. 

Scientific  publications  of  American  |  and  Ger- 
man §  origin  contain  accounts  of  a  process  of  cover- 
ing iron  electrolytically  with  aluminum,  which  is 
said  to  have  been  practically  carried  out  in  the 
factory  of  the  Tacony  Iron  and  Metal  Company,  at 
Tacony,  Pa. ;  more  exact  details,  which  from  a 
metallurgical  point  of  view  would  be  interesting, 
are,  however,  lacking. 

Felt  proposes  to  separate  •aluminum  in  an  appa- 
ratus which  is  depicted  in  Fig.  36,  the  purpose  of 
which  is  very  uncertain.  E  represents  the  cross- 
shaped  copper  cathode,  over  which  a  copper-wire 

*  D.  R.  P.  No.  46753. 

t  D.  R.  P.  No.  58136. 

$  Iron  Age,  1892,  Feb.  25  and  June  2. 

§  Stahl  und  Eisen,  1892,  Nos.  7  and  14. 


62 


PRODUCTION  OF  ALUMINUM. 


netting  G  hangs  from  above.  The  positive  electrode 
R,  which  is  located  in  the  upper  part  of  the  vessel, 
has  the  form  of  a  circular  grating,  and  consists 
of  zinc,  which  is  provided  with  quicksilver  chan- 
nels C  for  its  amalgamation.  A  parchment  dia- 
phragm H  divides  the  entire  cell  into  two  parts; 
the  tube  K  serves  as  a  means  of  emission  for  the 


FIG.  36. 

gases  developed  during  the  electrolysis.  As  an 
electrolyte  dilute  sulphuric  acid  is  employed,  which 
is  mixed  with  some  quicksilver  nitrate  dissolved  in  a 
hundred  times  its  weight  of  water ;  from  which  the 
quicksilver  found  in  the  set-in  vessel  0  is,  last  of 
all,  constantly  delivered.  The  aluminum  ore  P— 
of  pure  clay,  for  example — is  fed  upon  the  metal 
network,  and,  according  to  Felt,  is  decomposed 
into  silica,  which  falls  through  the  netting  and  is 
collected  at  the  bottom  of  the  apparatus,  and  into 
aluminum,  which  is  precipitated  upon  the  metal 
grating,  not,  however,  upon  the  other  parts  of 
the  cathode  E.  In  order  to  obtain  pure  aluminum, 


PROCESSES.  63 

one  of  the  surfaces  of  the  netting  is  lacquered  suffi- 
ciently so  that  the  metal  is  only  separated  at  the 
other  surface. — It  is  needless  to  say  that  of  this 
patent  as  well  as  of  all  others  of  this  group  no  sig- 
nificant use  has  been  made. 

Finally,  the  process  of  Whole  should  be  men- 
tioned, by  which  a  solution  of  alum,  electrolyzed  with 
the  addition  of  cyanide  of  potassium,  delivers  metal- 
lic aluminum. 

The  Electrolysis  of  Molten  Aluminum  Compounds. — 
Among  the  countless  processes  which  have  for  their 
object  the  production  of  aluminum  by  means  of 
the  electrolysis  of  its  molten  compounds,  there  are 
in  particular  but  three  \\rhich  have  found  and 
still  find  technical  employment,  namely,  those  of 
Heroult,  Minet,  and  Hall. 

On  looking  through  the  descriptions  of  patents 
relative  to  our  subject,  these  processes,  both  with 
regard  to  the  fundamental  idea  as  well  as  with 
respect  to  the  composition  of  the  electric  bath 
and  the  arrangement  of  the  apparatus,  do  not 
appear  to  differ  materially  from  other  processes 
of  the  same  group.  This  was  no  doubt  the 
reason  why  individual  authors  had  doubts  as  to 
the  practicability  of  the  processes  mentioned,  and 
attained  improvements  that  were  perhaps  too 
superficial,  so  that  these  processes  offer  nothing 
new.  If  one  inspects  them  yet  more  closely,  it  is 
plain  that  the  above-mentioned  processes  for  the 
electrometallurgy  of  aluminum  are  quite  novel, 


64  PRODUCTION  OF  ALUMINUM. 

and  are  related  only  very  distantly  to  their  pre- 
decessors. 

If  the  electrometallurgy  of  aluminum  was  to  be 
enabled  to  develop  on  a  secure  foundation,  it  was 
necessary  above  all  to  construct  substantial  appa- 
ratus, which  must  also  show  themselves  capable  of 
resistance  to  corrosive  materials  in  a  molten  con- 
dition— for  example,  fluoride — and  which  could  be 
harmed  neither  by  the  effect  of  the  electrolyte  nor 
by  the  length  of  an  operation.  Furthermore,  it  was 
necessary  to  secure  carbon  anodes  which,  together 
with  the  utmost  cheapness  and  a  slight  percentage 
of  impurities,  united  resistance  to  heat  with  a  good 
conductivity;  in  short,  the  problem  of  a  rational 
electrical  furnace  had  to  be  solved. 

Electrometallurgists  were,  then,  in  the  presence 
of  a  very  definite  problem;  it  is  true  that  as  early 
as  the  beginning  of  the  year  1887  electrolytic 
aluminum  had  been  put  upon  the  market,  yet  the 
processes  actually  capable  of  competition  in  the 
production  of  the  metal  date  only  from  a  later 
time — from  the  years  1890  and  1891;  and  through 
these  methods,  worked  out  with  precision  to  the 
utmost  detail,  not  merely  was  the  aluminum  in- 
dustry promoted,  but,  together  with  this  industry, 
electrometallurgy  as  a  whole. 

The  furnaces  which  originally  sufficed  merely  for 
the  requirements  of  the  electrolysis  of  melted 
compounds,  as,  for  example,  the  furnace  of  Heroult, 
could  later  be  used  without  material  alteration 


PROCESSES.  65 

in  electrothermic  processes  also,  as  in  the  pro- 
duction of  alloys,  of  metal  carbides,  metal  borides, 
and  metal  silicides. 

Davy  Process. — After  Davy  *  had  succeeded  in 
dissolving  the  alkali  hydrates  by  means  of  the 
electric  current,  he  attempted  in  the  year  1807  to 
apply  the  same  method  with  alumina  for  the  pro- 
duction of  metallic  aluminum;  he  reached,  how- 
ever, no  result,  owing  to  the  weakness  of  the  currents 
at  that  time  available  for  the  prosecution  of  his 
experiments.  Not  until  a  few  years  later, f  when 
he  resumed  his  investigations,  did  he  succeed  in 
producing  an  alloy  of  aluminum  and  iron,  and 
then  he  did  so  in  the  following  manner: 

A  platinum  plate,  which  was  connected  with 
the  positive  pole  of  a  galvanic  pile  of  1000  elements, 
was  covered  with  a  deposit  of  damp,  hard-pressed 
alumina,  into  which  an  iron  wire  was  introduced, 
which  was  in  connection  with  the  negative  pole  of 
the  pile.  The  wire  came  forthwith  to  a  red  glow 
and  melted  at  the  point .  of  contact.  The  mass 
was,  when  cooled  down,  more  brittle  than  iron,  and 
proved  to  be  an  alloy  of  iron  and  aluminum.  Cer- 
tainly the  latter,  in  this  reaction,  was  not  separated 
by  a  purely  electrolytic  process,  but  rather  by 
an  electrothermic,  which  to  some  extent  resembles 
the  methods  of  Cowles  and  Heroult. 


*  Philosophical  Transactions,  London,  1808. 
f  Ibid.,  1810. 


66 


PRODUCTION   OF  ALUMINUM. 


Bunsen  Process. — To  Bunsen  *  belongs  the  credit 
of  being  the  first  to  produce  pure  aluminum  by  the 
electrolytic  method  (1854);  and  this  he  did  by  the 
electrolysis  of  melted  aluminum  compounds.  He 
used  for  this  purpose  the  apparatus  which  two 
years  before  had  served  him  for  the  electrolytic 
production  of  magnesium  (Fig.  37),  and  which 


FIG.  37. 

now  rendered  him  notable  service  in  dissolving  the 
aluminum-sodium  double  chloride. 

Deville  Process.  —  Almost  simultaneously  with 
Bunsen,  Henri  St.  Claire  Deville  f  succeeded  in  ob- 
taining small  quantities  of  aluminum  electrically; 
likewise  through  dissolving  the  aluminum-sodium 
double  chloride. 

Undoubtedly  the  French  investigator,  when  on 
the  1 4th  of  August,  1854,  he  described  his  investi- 
gations before  the  Academy  of  Sciences,  had  as  yet 
no  knowledge  of  the  researches  of  Bunsen,  which 

*  Poggendorffs  Annalen,  XCII,  1854. 

f  Ann.  de  chimie  et  de  physique,  XLIII  (1854),  p.  27. 


PROCESSES. 


67 


only  shortly  before,  on  July  pth,  had  appeared  in 
Poggendorffs  Annalen.  But,  even  though  he  made 
no  mention  of  this  last  publication  of  Bunsen,  he 
did  not  omit  in  his  communication  to  refer  to 
the  process  by  which  Bunsen  in  1852  had  produced 
magnesium  by  the  electrolysis  of  its  chloride,  and 
to  acknowledge  "that  the  German  investigator 
has  here  indicated  a  method  that  might  lead  to 
interesting  results  in  widely  different  directions." 
The  apparatus  of  which  the  French  savant  availed 
himself  consisted  of  a  porcelain  crucible  P  (Fig.  38), 


FIG.  38. 

which  was  set  into  a  Hessian  crucible  H\  the  whole 
was  closed  with  a  lid  D,  in  which  there  were  two 
openings,  a  small,  slit-like  one  for  the  platinum 
sheet  K  serving  as  the  negative  electrode  and  a 
larger,  circular  one  for  the  introduction  of  the 


68  PRODUCTION  OF  ALUMINUM. 

porous  cylinder  R.  Into  the  latter  was  plunged 
the  bar-shaped  anode  A,  which  consisted  of  re- 
tort-carbon. Between  the  bottom  of  this  cylinder 
and  that  of  the  crucible  was  left  a  margin  of  several 
centimetres. 

The  crucible  and  the  cell  were  filled  to  the  same 
height  with  molten  aluminum-sodium  chloride, 
which  was  produced  by  heating  a  mixture  of  2  parts 
anhydrous  aluminum  chloride  and  i  part  sodium 
chloride.  These  two  salts  unite  at  about  200°  C. 
with  a  release  of  heat,  whereby  an  easily  flowing 
substance  is  produced  which  at  the  least  rise  in 
temperature  gives  off  abundantly  vapors  of  alu- 
minum chloride. 

With  the  passage  of  the  current,  the  aluminum 
chloride  is  dissolved;  the  chlorine  migrates  to  the 
anode  A  and  there  escapes.  The  aluminum  sepa- 
rates off  at  the  cathode  K,  whence  from  time  to 
time  it  is  removed,  while  the  electrode  is  taken 
out  of  the  bath  and  allowed  to  cool.  In  this  way 
small  quantities  of  aluminum  are  eventually 
obtained,  in  the  form  of  a  metallic  residuum. 

In  order  to  keep  the  proportion  of  aluminum  in 
the  melt  constant,  Deville  *  recommends  anodes 
which  consist  of  a  pressed  mixture  of  aluminum 
oxide  and  carbon.  This  process  was  later  taken 
up  again  by  Le  Chatelier  and  Lontin;  I  myself 
always  added  to  my  anode  material  some  parts  of 

*  H.  St.  Claire  Deville,  Aluminium,  p.  95,  Paris,  1859. 


PROCESSES.  69 

aluminum  oxide,  but  less  to  prevent  variations  in 
the  composition  of  the  bath  than  to  give  an  in- 
creased firmness  to  the  anodes. 

Gaudin  Process.* — This  depends  upon  the  elec- 
trolysis of  a  fused  mass  of  cryolite  and  chloride  of 
sodium.  By  means  of  the  current  the  fluoride  is 
dissolved,  fluorine  is  separated  at  the  positive, 
aluminum  at  the  negative  pole.  More  exact  de- 
tails are  not  known. 

Kagenbusch  Process f  (1872).  —  Clay  is  melted 
with  the  aid  of  fluxes,  and,  after  the  addition  of 
zinc,  electrolyzed ;  the  zinc  alloys  itself,  it  is  stated, 
with  aluminum,  and  may  be  separated  from  the 
latter  by  distillation  or  by  a  winnowing  process.' 

The  patents  of  Berthaut  J  (1879;  similar  to  the 
process  of  Deville)  and  of  Faure  (1880),  who  dis- 
solves aluminum  chloride  electrolytically,  we  here 
mention  merely  for  the  sake  of  completeness,  with- 
out going  further  into  a  description  of  the  details 
of  the  apparatus. 

Lontin  Process.  —  Even  though  the  researches 
of  this  investigator  of  the  question  of  aluminum 
production,  which  began  before  1880  and  ended 
only  with  his  death  (1886),  reached  no  final  con- 
clusion, they  are  nevertheless  of  an  abiding  impor- 
tance in  electrometallurgy,  in  consequence  of  their 


*  Moniteur  scientifique,  XI,  p.  62,  according  to  J.  W.  Richards, 
Aluminium,  26.  Ed.,  London,  1890. 

f  Engl.  Pat.  No.  4811,  1872;  Richards,  loc.  cit. 
j  Engl.  Pat.  No.  4087,  1879. 


70  PRODUCTION  OF  ALUMINUM. 

practicability  and  their  precision — qualities  which, 
indeed,  characterize  all  of  Lontin's  operations ;  and 
if  to-day  we  must  acknowledge  that  the  electro- 
metallurgy of  our  metal,  thanks  to  the  patents 
of  Heroult,  Hall,  and  Minet — which,  moreover, 
are  so  similar  that  they  seem  almost  to  form  one 
process, — rests  upon  a  firm  foundation,  to  Lontin 
belongs  the  credit  of  having  been  their  predecessor. 

In  his  researches  (1882)  he  proceeded  from  the 
electrolysis  of  a  melt  in  which  alumina  was  dis- 
solved, and  which  doubtless  formed  a  mixture  of 
cryolite  and  common  salt,  and  hence  had  the 
same  composition  as,  later,  the  baths  of  Heroult 
and  Hall. 

In  1886  Lontin  presents  his  first  proposal;  it 
is  true  he  retains  the  cryolite-salt  melt;  he  does 
not,  however,  add  to  this  alumina,  but,  reverting 
to  the  earlier  arrangement  of  Deville,  employs 
simply  an  anode  which  consists  of  a  carbon-alumina 
compound.  In  the  process  Lontin  supposes  that 
the  current  in  the  electrolysis  decomposes  only  the 
sodium  chloride,  and  not  the  cryolite  as  well. 
The  chlorine  which  separates  at  the  positive  elec- 
trode is  united  with  A12O3  and  forms  A12C16 
which  mixes  with  the  bath.  As  soon  as  the  alu- 
minum chloride  has  passed  beyond  a  certain  point 
in  concentration,  only  the  chloride  and  no  longer 
the  salt  is  decomposed  by  the  current.  From  this 
moment  aluminum  is  given  off  at  the  cathode,  in  a 
molten  state,  since  the  temperature  of  the  bath  is 


PROCESSES.  71 

higher  than  that  of  the  metal,  while  at  the  anode 
the  chlorine  developed  conies  into  reaction  with 
the  mass  of  alumina  equivalent  to  the  separated 
aluminum  chloride. 

It  is  true  that  Lontin,  in  these  researches  ter- 
minated all  too  soon  by  his  premature  death,  reached 
no  final  result;  yet,  as  we  have  already  remarked, 
by  his  efforts  the  way  to  the  goal  was  made  plain. 

Graetzel  Process.* — This  depends  upon  the  elec- 
trolysis of  a  quantity  of  melted  chloride  and  fluor- 
ide. The  apparatus  (Fig.  39)  consists  of  a  melt- 


FIG.  39. 

ing- vessel  of  porcelain,  stoneware,  or  some  other 
suitable  fire-resisting  material,  which  is  protected 
from  direct  contact  with  the  fire-gases  by  a  metal 
mantle.  The  vessel  has  an  inner  lining  of  metal, 
preferably  aluminum,  which  serves  as  a  cathode. 

*D.  R.  P.  No.  26962. 


72         PRODUCTION  OF  ALUMINUM. 

The  anode  is  formed  by  a  carbon  rod  K,  which  is 
enclosed  in  a  porcelain  tube  G,  provided  with 
slot-openings  g  and  a  tube  p  for  the  release  of  the 
chlorine. 

During  the  electrolysis  a  reducing-gas  is  conducted 
through  the  apparatus,  entering  at  Of  and  escap- 
ing at  O2.  In  order  to  lessen  the  pressure,  and 
in  order  simultaneously  to  add  to  the  bath  fresh 
material  according  to  the  rate  of  exhaustion,  there 
are  in  the  porcelain  tube  G,  at  both  sides  of  the 
carbon  electrode  and  not  having  '  any  contact 
with  it,  plates  or  bars  M,  which  consist  of  a  com- 
position of  equivalent  quantities  of  alumina  and 
carbon. 

This  process,  which  may  be  classed  with  the 
Lontin  process  for  aluminum,  has  never  been 
technically  applied,  and  even  its  inventor,  accord- 
ing to  the  statement  of  Borchers,  in  his  capacity 
as  director  of  the  Hemlinger  Aluminum  and  Mag- 
nesium Works  has  made  use,  in  obtaining  alu- 
minum, not  of  his  own  patent,  but  of  the  patent 
of  Beketoff,  which  depends  upon  the  reduction  of 
cryolite  by  means  of  magnesium. 

Boguski-Zdziarski  Process*  (1884). — This  patent 
had  for  its  object  principally  the  production  of 
aluminum  alloys.  Its  similarity  to  the  Lontin 
method  may  be  seen  from  the  subjoined  descrip- 
tion of  the  patent:  Cryolite  or  other  aluminum 

*  Engl.  Pat.  No.  3090,  1884. 


PROCESSES.  73 

compounds  were  mixed  with  the  appropriate 
fluxes  and  smelted  in  an  iron  or  graphite  cru- 
cible heated  by  flame-gases.  On  the  bottom  of 
the  crucible  the  metal  is  found  which  is  alloyed 
with  aluminum.  The  cathode  during  the  electroly- 
sis is  the  alloy  itself,  while  a  bar  of  carbon  dipped 
into  the  melt  serves  as  anode. 

Farmer  Process*  (1885).  —  This  rests  upon  the 
electrolysis  of  molten  aluminum  chloride  in  a 
crucible  whose  conducting  walls  form  the  cathode. 

Grousilliers  Process  f  (1885).  —  In  order  to  avoid 
the  very  considerable  loss  of  aluminum  chloride  by 
evaporation,  owing  to  the  high  temperature  of  the 
electrolytic  cell,  Grousilliers  recommends  electroly- 
sis under  pressure  in  closed  vessels. 

Grabau  Process.  J  — Among  the  impurities  of  alu- 
minum produced  electrolytically  from  molten  fluor- 
ides, we  have  to  take  into  account  principally 
those  that — like  iron  and  silicon — in  consequence 
of  the  more  or  less  strong  effect  of  the  bath  upon 
the  walls  of  the  vessel  owing  to  the  temperature- 
relations  and  the  contained  fluoride,  are  among  the 
last  to  be  successfully  melted. 

With  cooled  pole-cells  Grabau,  therefore,  hopes 
to  obtain  pure  aluminum  by  the  following  process: 
In  the  electrolytic  dissociation  of  a  molten  bath 
of  cryolite  and  common  salt,  we  know  that  chlorine 


*U.  S.  A.  P.  No.  315266. 
t  D.  R.  P.  No.  34407. 
%  D.  R.  P.  No.  45012. 


74 


PRODUCTION  OF  ALUMINUM. 


is  separated  at  the  positive,  molten  aluminum  at 
the  negative  pole.  Since  molten  cryolite  affects 
every  fire-proof,  non-conducting  material,  the  parts 
of  the  apparatus  concerned  must  be  protected  by 
an  invulnerable  insulating  covering  from  the  effect 
of  the  bath  or  of  the  elements  separated  therefrom. 
Grabau  attains  this  end  by  means  of  the  follow- 
ing device  (Fig.  40). 


FIG.  40. 

A  is  an  iron  melting-vessel,  which  is  heated  from 
the  outside  by  fire-gases  to  such  a  degree  that  the 
molten  material  remains  in  an  easily  flowing  state ; 
its  level  mounts  to  XX.  B  is  a  double-walled 
metal  cell  of  ring-shaped  cylindrical  form,  which 
is  cooled  with  air  or  water.  The  flowing  aluminum 


PROCESSES.  75 


separated  is  assembled  in  a  trough-shaped  collect- 
ing-vessel C,  which  is  likewise  provided  with 
double  walls,  between  which  air  or  water  circulates. 
In  consequence  of  the  cooling  thus  brought  about 
the  molten  mass  congeals  on  the  entire  surface 
of  the  cell,  of  the  collecting-vessel  and  the  con- 
ducting-tubes  rrf  and  r2r3,  and  the  non-conducting 
crust  K  formed  hereby  cannot  be  attacked  either 
by  the  smelting  or  by  the  aluminum. 

In  my  opinion,  an  apparatus  of  this  sort  is  not 
practicable;  at  least,  it  would  not  accomplish  the 
object  intended  by  the  inventor,  since  he  has  un- 
doubtedly overlooked  the  fact  that  the  iron  outer 
vessel  A  is  affected  by  the  melt.  Iron  salts  will 
be  formed  which  mingle  with  the  bath,  and  accord- 
ing to  the  proportions  of  their  composition  are 
dissolved  by  the  current,  so  that  the  aluminum 
precipitated  under  these  conditions  will  always 
contain  a  large  percentage  of  iron.  In  order  to 
obtain  better  results,  the  vessel  A  would  have  to 
be  cooled  to  the  same  degree  as  the  cell  B  and  the 
containing  vessel  C\  in  that  event,  however,  the 
heat  from  outside  would  fall  off,  and  the  additional 
warmth  necessary  for  the  production  of  the  molten 
flow  would  be  taken  away  from  the  work  of  the 
current. 

He*roult's  First  Process*  (1886).— By  this  patent, 
similar  to  the  first  Lontin  process,  a  solution  of 
alumina  is  subjected  to  electrolysis  in  molten 

*  Engl.  Pat.  No.  7426,  1887  — Henderson-Mandataire. 


76 


PRODUCTION  OF  ALUMINUM. 


cryolite,  whereby  a  quantity  of  alumina  equivalent 
in  amount  to  the  metal  separated  is  continually 
replaced.  The  crucible  A  (Fig.  41),  which  is  heated 


FIG.  41. 

from  without,  consists  of  carbon  and,  at  the  same 
time,  forms  the  cathode.  It  is  surrounded  by  a 
second  crucible  B  of  graphite,  which  serves  as  a 
protecting  envelope;  the  space  between  these  two 
crucibles  is  filled  with  graphite  powder.  The  con- 
tact with  the  external  circuit  is  brought  about  by 
the  carbon  bar  Ef,  which  is  enwrapped  by  the 
clay  tube  D'.  The  carbon  anode  E,  which  is  like- 


PROCESSES.  77 

wise  protected  by  a  clay  tube  JD,  is  introduced 
into  the  bath  through  an  opening  in  the  roof  G. 
The  latter  is  covered  with  a  deposit  of  alumina. 
The  entire  apparatus  rests  upon  a  support  of  fire- 
clay. For  the  electrolysis  an  electromotive  force 
of  3  volts  is  sufficient. 

The  patent  of  Henderson,  according  to  his  descrip- 
tion, is  similar  to  the  majority  of  processes  that 
have  actually  passed  into  technical  employment; 
it  seems  to  me,  however,  that  its  introduction  in 
practice  has  not  been  seriously  contemplated  even 
by  the  inventor. 

Lossier  Process.*  —  A  composition  of  melted 
cryolite  and  sodium  chloride  is  electrolyzed  under  a 
gradual  addition  of  silicate  of  alumina  or  kaolin. 
In  this  way,  however,  pure  aluminum  cannot  be 
obtained,  but  merely  a  metal  containing  a  large 
percentage  of  silicon. 

According  to  a  process  similar  to  one  of  the 
Lossier  patents — the  addition  of  bauxite  to  a  bath 
of  aluminum  fluoride — the  author  has  succeeded 
under  very  advantageous  conditions  in  obtaining 
a  ferro-silicon  aluminum  which  may  be  employed 
directly  for  the  refining  of  steel;  this  process,  how- 
ever, seems  as  yet  to  have  met  with  no  favor  among 
metallurgists. 

In    conclusion    we    may    mention    the    Rogers  f 

*  D.  R.  P.  No.  31089. 

t  Proceedings  of  the  Wisconsin  Natural  History  Society, 
April  1899.  Richards,  loc.  cit. 


78  PRODUCTION  OF  ALUMINUM. 

process,  which  depends  upon  the  electrolysis  of 
molten  cryolite  with  cathodes  of  melted  lead; 
then  the  patent  of  A.  Winkler*  (Gorlitz),  the  idea 
of  which  is,  however,  conceived  from  a  point  of  view 
wholly  erroneous,  since  the  patent  recommends  the 
electrolysis  of  alumina  phosphates  and  borates ;  and 
finally  the 

Feldmann  Process f  (1887),  according  to  which  a 
composition  of  aluminum-sodium  double  fluoride 
with  barium  chloride,  strontium  chloride,  calcium 
chloride,  magnesium  chloride,  and  zinc  chloride,  or 
else  (1889)  a  mixture  of  aluminum  haloid  salts  with 
the  oxides  of  electropositive  metals,  is  electrolyzed. 

Among  all  the  processes  thus  far  explained  for 
the  electrolytic  separation  of  aluminum,  there  is 
found  none  which  is  of  industrial  insignificance.  Of 
technically  important  processes  there  are  but 
three,  namely,  those  of  Minet,  Heroult,  and  Hall. 
These  will  be  described  in  detail  in  the  following 
pages. 

Minet    Process. 

I  had  a  twofold  aim  in  my  researches  upon  the 
electrometallurgy  of  aluminum. 

On  the  one  hand,  I  sought  to  find,  for  a  metal 
with  such  a  promising  future,  the  most  economical 
method  of  production ;  on  the  other  hand,  I  wished 

*D.  R.  P.  No.  45824. 

t  D-  R.  P.  No.  49915,  1887. 


PROCESSES.  79 

to  solve  a  problem  of  much  more  universal  signifi- 
cance— the  problem  of  the  electrolysis  of  anhydrous, 
molten  electrolytes. 

We  know  that  the  electric  current  is  able  to 
operate  in  two  ways — electrolytically  and  electro- 
thermically.  The  researches  of  the  author  have 
been  chiefly  of  an  electrolytic  nature,  though 
in  many  of  the  furnace  constructions  electrothermic 
principles  have  been  involved. 

Since  in  my  investigations  I  made  the  universal 
characteristics  of  the  electric  current  my  point  of 
departure,  I  came  straightway  upon  its  capacity — 
of  such  great  technical  significance — for  storing  up 
large  amounts  of  energy  within  a  limited  space; 
a  principle  which  may  perhaps  be  expressed  as 
follows :  No  matter  by  what  method,  from  a  physical 
point  of  view,  an  electrical  phenomenon  may  be 
produced,  whether  it  is  an  effect  of  light  or  of  heat, 
an  electrolytic  or  an  electrothermic  process,  the 
utilization  of  the  energy  assembled  by  means  of 
the  electricity  is  the  greater,  the  smaller  the  space 
in  which  the  reaction  takes  place. 

I  ascribe  it  solely  to  the  fact  of  my  adhering  as 
closely  as  possible  to  this  principle,  whose  cor- 
rectness, indeed,  is  evident  from  what  has  been 
already  said,  that  I  was  able  through  my  efforts, 
which  date  from  February  1887,  to  solve  the 
problem  of  the  electrolytic  production  of  alumi- 
num, from  its  molten  salts.  It  is,  however,  the 
same  principle  upon  the  basis  of  which  Cowles  and 


8o  PRODUCTION  OF  ALUMINUM. 

Heroult  succeeded  in  producing  electrothermically 
the  copper  and  iron  alloys  of  aluminum,  and  which 
Moissan  and  Bullier  were  later  to  apply  in  order 
to  obtain  crystallized  calcium  carbide;  and  if 
Willson  was  able  to  produce  only  slightly  denned 
carbides,  this  was  largely  because  of  a  neglect  on 
the  part  of  this  investigator  to  heed  the  principle 
I  have  mentioned. 

The  electrolytic  decomposition  of  fire-melted 
materials  had  found  but  a  limited  application  until 
there  was  a  successful  electrometallurgical  pro- 
cess of  producing  aluminum.  This  method  of 
decomposition  was  employed  under  certain  circum- 
stances in  chemistry  for  scientific  purposes — for  ex- 
ample, in  order  to  effect  the  decomposition  of  material 
reducible  with  difficulty;  and  though  the  same 
method  was  also  proposed  for  the  production  of 
certain  metals,  such  as  the  alkalies  and  alkaline 
earths,  the  investigations  in  this  domain  were 
limited,  at  least  so  far  as  regards  any  industrial 
application. 

In  my  efforts  to  bring  upon  the  market  electro- 
lytic aluminum  as  cheaply  as  possible,  and  in  large 
quantities,  I  have  at  the  same  time  sought  to  find 
the  best  conditions  for  the  electrolysis  of  molten 
salts  in  particular.  With  reference  to  this  question 
we  must  consider:  the  composition  of  the  bath, 
its  temperature,  movement,  density,  unchange- 
ableness,  constancy,  the  dimensions  of  the  electrodes 
and  of  the  crucible  which  contains  the  melt,  and 


PROCESSES.  8 1 

finally  the  nature  of  the  various  parts  of  the  appa- 
ratus. That  these  results  could  be  reached  only 
through  special  devices  and  by  the  use  of  new 
apparatus  goes  without  saying. 

In  the  proof  of  a  theoretical  interpretation  of 
the  observed  phenomenon  one  obtains  a  formula 
which  unites  the  constants  of  the  current  with  those 
of  the  electrolyte,  for  the  three  stages  of  the  begin- 
ning, the  course,  and  the  conclusion  of  the  elec- 
trolysis. 

The  first,  part  of  my  researches  occupied  two 
years;  during  this  time  my  method  was  used 
industrially  in  two  places,  in  Paris,  Impasse  du 
Moulin- Joli  (1887),  and  in  Creil  (1888);  later  the 
establishment  in  Creil,  where  I  could  avail  myself 
of  only  one  3o-horse-power  steam-engine,  was 
transferred  to  Saint-Michel  de  Maurienne  (1891), 
where  I  worked  up  to  the  year  1894  with  a  water- 
power  of  500  H.P. — For  the  means  of  carrying  out 
my  experiments  I  have  to  thank  the  Bernard 
brothers. 

Choice  of  the  Electrolyte. — There  are  three  kinds 
of  aluminum  salts,  which  in  a  molten  condition  may 
be  subjected  to  electrolysis:  the  haloid  salts,  that 
is  to  say,  those  in  which  the  acid  radical  is  a  halogen ; 
the  oxy-  or  double  salts,  consisting  of  aluminum 
oxide,  combined  or  mixed  with  an  aluminum- 
halogen  salt;  and  finally,  according  to  the  state- 
ment of  some  inventors,  the  sulphides.  I  myself, 
in  continuing  the  investigations  of  Deville  and 


82  PRODUCTION  OF  ALUMINUM. 

Lontin,  concerned  myself  chiefly  with  the  chloride 
and  the  fluoride  of  aluminum. 

The  melting-point  of  the  pure  fluoride  lies  at  a 
very  high  temperature,  and  indeed  so  near  the 
boiling-point  that  upon  heating  it  passes  directly 
from  the  solid  into  the  gaseous  state.  But  even 
if  one  could  keep  it  molten  for  a  sufficiently  long 
time,  it  would  nevertheless  not  allow  itself  to  be 
electrolyzed,  since,  like  all  pure  salts,  it  is  a  poor 
electric  conductor  in  the  molten  state;  in  order  to 
increase  its  conductivity  it  must  be  combined  with 
the  salt  of  another  metal,  for  example,  sodium 
fluoride — that  is  to  say,  a  double  salt  must  be 
formed. 

Aluminum  chloride  melts  at  a  low  temperature 
(185°  C.),  and  shows  with  regard  to  melting  the 
same  appearance  as  the  fluoride;  like  the  fluoride, 
also,  it  is  not  a  good  conductor  until  it  becomes  a 
double  salt. 

For  electrolyte  I  used  the  following  compounds: 
on  the  one  hand  40  parts  aluminum-sodium  double 
chloride  and  60  parts  sodium  chloride,  on  the  other 
hand  40  parts  aluminum-sodium  double  fluoride  and 
likewise  60  parts  sodium  chloride. 

The  aluminum  chloride  is  also  uncommonly 
volatile  as  a  double  salt,  even  when  it  is  mixed 
with  an  excess  of  alkali-salt;  at  the  slightest  rise 
in  temperature  corrosive  vapors  arise  from  the  bath, 
which  make  more  difficult  the  control  of  the  elec- 
trolysis and  are  not  without  attendant  risk. 


PROCESSES.  83 

A  bath  with  aluminum  fluoride  as  the  chief  ele- 
ment gives  the  best  result. 

Properties  of  the  Electrolyte. — The  composition  of 
the  melt,  as  I  finally  decided  upon  it,  is  expressed 
in  the  formula 

i2NaCl  +  Al2F6.6NaF. 

Its  melting-point  lies  at  675°  C.;  at  1056°  C.  it 
begins  to  evaporate;  its  density  at  829°  C.  amounts 
to  1.76;  its  coefficient  of  expansion  in  the  molten 
state  is  5.10 ~5;  its  specific  conductivity  at  870°  C. 
is  3.1,  and  therefore  its  specific  resistance  is  0.323 
ohm.  If  Ct  is  the  specific  conductivity  and  Rt  the 
specific  resistance  at  the  temperature  t,  we  have  the 
formula 

^=3. i[i +0.00334(^-870°)], 
Rt  0.323 


i +0.00334(^-870°  C)' 

For  a  current  strength  of  4000  amp.  the  charge 
amounts  to  60  kg.  At  800°  C.  the  melt  is  suffi- 
ciently fluid  to  maintain  the  electrolysis  uninter- 
ruptedly, and  at  the  same  time  is  so  slightly  vola- 
tile that  the  losses  in  consequence  of  evaporation 
during  24  hours  do  not  exceed  5%. 

The  bath  unites  in  itself  the  best  possible  con- 
ditions for  work.  If  its  properties — its  melting- 
point,  its  density  at  870°  C.,  etc. — are  compared 
with  the  corresponding  properties  of  metallic  alu- 
minum, the  truth  of  the  assertion  will  appear  that 


84  PRODUCTION   OF  ALUMINUM. 

we  meet  with  scarcely  another  instance  in  metal- 
lurgy where  there  is  such  a  favorable  coincidence. 

Since  aluminum,  as  we  know,  melts  at  625°  C., 
it  is  already  separated  in  a  fluid  state  by  electrolysis^ 
at  the  bath-temperature  of  870°  C.;  since,  further- 
more, its  density  (2.63)  is  considerably  higher  than 
that  of  the  electrolyte  (1.76),  the  metal  simply 
flows  off  along  the  cathode  and  is  assembled  at  the 
bottom  of  the  crucible,  whence  it  may  be  drawn  off 
through  a  tapping- vent. 

How  widely  the  electrometallurgical  production 
of  aluminum  differs  in  this  respect  from  that  of 
the  other  metals,  the  following  comparison  will 
show.  As  the  average  density  of  the  substances 
subjected  to  the  electrolysis  in  a  molten  state — 
potassium,  sodium,  magnesium,  lithium,  beryllium — 
we  may  take  1.75.  Since,  now,  the  density  of 
potassium  is  0.87,  of  sodium  0.97,  of  lithium  0.59, 
the  metals  mentioned,  in  contrast  to  aluminum, 
are  not  assembled  at  the  bottom  of  the  crucible, 
but  rise  upward,  where  by  means  of  special  con- 
trivances they  must  be  united  and  prevented  from 
oxidation  by  air. '  With  magnesium  and  beryllium 
the  metal-density  and  the  bath-density  are  not 
materially  different  (1.76  and  1.73  as  compared 
with  1.75);  the  metals,  therefore,  remain  floating 
in  the  melt,  and  are  assembled  only  in  a  form  of 
the  apparatus  constructed  for  the  purpose. 

As  for  the  temperature  of  the  melt,  the  relations 
in  the  majority  of  electrolytic  baths  are  in  so  far 


PROCESSES. 


favorable,  that  the  temperature  generally,  without 
impairing  the  ready  movement  of  the  electrolyte, 
is  sufficiently  far  below  the  boiling-point  of  the 
metal  concerned,  but  above  the  melting-point. 

Decomposition-voltage  of  the  Electrolyte.  —  Upon 
the  passage  of  the  current,  the  aluminum  chloride 
is  first  dissolved,  since  this  chloride,  of  all  salts 
present,  has  the  lowest  decomposition- voltage. 


Name. 

Equivalent 
Formula. 

Heat  of 
Formation, 
Cal. 

Decomposi- 
tion-voltage, 
Volts. 

Aluminum  fluoride 

Al2/RF 

7O 

3O4. 

Sodium  chloride 

NaCl 

Q7       7 

42  3 

Sodium  fluoride      ... 

NaF 

1  10  8 

4.    82 

The  heat  of  formation  of  aluminum  fluoride,  it  is 
true,  has  not  been  experimentally  determined,  yet 
it  may  be  estimated,  when  we  take  into  considera- 
tion the  following  facts:  Upon  comparing  the 
other  halogen  salts  of  aluminum  (chloride,  bromide, 
iodide)  with  the  corresponding  potassium  haloids, 
one  finds  between  the  pairs  of  homologous  mem- 
bers an  equal  and  constant  difference  of  51.75  cal. 
One  may  therefore  justly  assert  that  between  the 
heats  of  formation  of  aluminum  fluoride  and  potas- 
sium fluoride  there  exists  a  like  difference.  Now, 
the  heat  of  formation  of  potassium  fluoride  has 
been  experimentally  determined  to  be  118.1  cal., 
and  therefore  the  heat  of  formation  of  aluminum 
fluoride  amounts  to  118.1  —  51.75=66.35  cal.  A 
wholly  analogous  comparison  between  the  aluminum 


86  PRODUCTION   OF  ALUMINUM. 

and  the  hydrogen  haloids  gives  for  the  heat  of 
formation  of  the  aluminum  fluoride  73.7  cal.  If 
we  take  the  average  of  the  two  figures,  we  obtain 
for  the  desired  heat  of  formation  70  cal. 

The  decomposition-voltage  is  reckoned  by  the 
universal  formula 

0  =  0.04346  C, 

if  C  is  taken  to  signify  the  equivalent  heat  of 
formation  of  the  electrolyte.  For  aluminum  fluo- 
ride we  obtain,  then  (see  Appendix,  page  218). 

e  =0.04346  X  70  =  3 .04  volts, 

which  value  is  introduced  into  the  table  above. 

Electrolysis.  —  The  electric  current  brings  about 
the  decomposition  of  the  aluminum  double  salt  into 
aluminum,  which  is  separated  at  the  negative  pole, 
and  into  chlorine,  which  is  formed  at  the  positive 
electrode,  while  the  released  sodium  fluoride  remains 
unaltered  in  the  melt.  The  process  is  expressed 
in  the  following  equation: 

Al2/6F.NaF  =  Alv,  +  F  +  NaF. 

Upon  the  passing  through  of  96435  coulombs, 
the  reaction  takes  place  according  to  the  stoichi- 
ometric  quantities  expressed  in  this  equation. 

Should  it  finally  be  desired,  according  to  the 
scale  on  which  the  decomposition  takes  place,  to 
enlarge  the  bath  by  the  addition  of  fresh  quantities 
of  cryolite,  the  melt  would  be  so  greatly  enriched 


PROCESSES.  87 

with  sodium  fluoride  that  the  latter  substance 
would  at  once  be  present  in  excess,  so  that  one 
would  then  obtain  in  the  electrolysis,  not  aluminum, 
but  sodium.  This,  indeed,  is  capable  of  experi- 
mental verification.  In  order  to  avoid  this  result 
the  two  following  methods  may  be  adopted. 

Regeneration  of  the  Bath  by  means  of  Aluminum 
Fluoride. — Into  the  bath  while  the  electrolysis  is 
going  on  aluminum  fluoride  is  introduced  in  quan- 
tities equivalent  to  the  sodium  fluoride  released,  so 
that  the  percentage  of  aluminum  in  the  electrolyte 
remains  constant.  The  aluminum  fluoride  added 
unites  with  sodium  fluoride  according  to  the  equa- 
tion 

A12/6F  +  NaF  =  A1./.F.  NaF. 

To  every  regenerated  g-molecule  there  corresponds, 
at  the  negative  pole,  2/6  g-atoms  of  aluminum, 
while  at  the  positive  pole  a  g-atom  of  fluorine 
escapes. 

Regeneration  by  means  of  Alumina. —  The  regen- 
eration follows  as  a  consequence  of  the  fact  that 
during  the  electrolysis  alumina  is  deposited  in  the 
form  of  a  fine  powder  in  the  neighborhood  of  the 
anodes.  There  are  two  principal  hypotheses  as 
to  the  reaction  that  takes  place  in  this  case. 

i.  The  alumina,  whether  it  unites  with  the 
released  sodium  fluoride  or  is  simply  dissolved  in 
the  molten  mass,  is  electrolyzed  simultaneously  with 
the  aluminum  fluoride,  since  its  equivalent  heat  of 


88  PRODUCTION  OF  ALUMINUM. 

formation  (65  cal.)  very  nearly  approaches  that 
of  the  aluminum  fluoride.  In  what  form  the 
alumina  is  contained  in  the  melt  is,  as  we  have 
said,  not  demonstrated.  It  may  on  the  one  hand 
unite  with  a  molecule  of  aluminum  fluoride  for  an 
oxide-fluoride  of  the  formula  A1»AOV,.A1V(,F,  where- 
by a  molecule  NaF  is  released;  on  the  other  hand 
it  may  also  form  directly  an  oxide  -fluoride  of  the 
composition  Aly6Oi/)2.NaF. 

Heroult  and  Hall,  who  accept  these  hypotheses, 
are  of  the  opinion  that  it  is  almost  exclusively 
alumina  which  is  decomposed  by  the  electric  current. 
At  the  negative  electrode  aluminum  is  freed;  at 
the  positive  pole  oxygen  separates  off,  which 
violently  attacks  the  electrode-carbon.  The  pro- 
cess is  expressed  in  the  equation 


It  is  a  fact  that  the  anode  in  time  becomes  much 
corroded;  and  this  effect  is  in  proportion  to  the 
quantity  of  aluminum  separated  off. 

2.  According  to  a  second  hypothesis,  it  is  accepted 
as  a  fact  that  the  work  of  the  current  limits  itself 
exclusively  to  the  aluminum  fluoride.  According  to 
this  conception,  the  alumina  serving  for  the  regener- 
ation is  converted  at  the  anode,  by  the  fluorine 
there  developed,  into  aluminum  fluoride,  according 
to  the  formula 


PROCESSES.  89 

the  aluminum  fluoride  formed  unites  with  the  free 
sodium  fluoride  to  form  a  double  salt: 

.    AL./.F  +  NaF = Al2/6F.NaF, 

and  oxygen  escapes.     (See  Appendix,  page  218). 

I  consider  this  second  hypothesis  the  more  prob- 
able. In  its  favor,  moreover,  is  also  the  circum- 
stance that  the  fluorine,  in  its  effort  to  develop  at 
the  anode,  is  not  completely  absorbed  by  the 
added  alumina,  so  that,  if  the  composition  of  the 
bath  is  to  be  kept  constant,  in  addition  to  alumina 
interchanging  quantities  of  aluminum  fluoride  must 
be  added  to  the  melt. 

Through  the  successive  addition  of  a  composition 
of  common  salt  and  aluminum-sodium  double 
fluoride,  in  the  proportions  given  above,  the  losses 
due  to  evaporation  are  compensated  for,  and  the 
level  of  the  bath  is  kept  at  the  same  point. 

Electrolytic  Constants.  —  Of  the  three  constants 
here  coming  under  observation,  the  counter-electro- 
motive force  e,  the  resistance  p,  and  the  potential 
difference  at  the  electrodes  E,  we  have  already 
defined  e\  it  remains  therefore  to  examine  more 
closely  the  two  other  quantities,  p  and  E. 

The  resistance  p  varies  with  the  proportion  of 
double  salt  contained  in  the  bath,  and  with  the 
dimensions  of  the  electrodes. 

The  four  baths  A-D  in  the  following  table  had  the 
same  composition — 70  parts  common  salt  and  30 
parts  double  fluoride,  with  an  insignificant  percent- 


PRODUCTION  OF  ALUMINUM. 
TABLE  I. 


Bath. 

Temperature, 
Deg.  C. 

Resistance, 

n. 

Dissolving-tension  , 
Volts. 

A 

900 
IOOO 
,    IIOO 

o  .0044 
0.0033 
o  .0025 

2.4 

2-3 
2.17 

B 

870 

o  .024 

2.50 

C 

870 

•o  .0012 

2.50 

D 

870 

0.0071 

2.50 

age  of  silicon  and  iron,  which,  however,  at  the 
beginning  of  the  operation  was  speedily  removed 
by  the  electrolysis  itself;  merely  the  size  of  the 
electrodes  was  different  in  the  four  baths. 

The  potential  difference  E  was.  determined  at 
three  different  times:  before,  during,  and  after  the 
electrolysis. 

i.  Measurements  before  the  Beginning  of  the 
Electrolysis. — The  bath  B,  in  which  the  experiments 
were  begun,  was  covered  with  a  melt  of  the  above 
mentioned  composition;  the  percentage  of  silicates 
and  iron  salts  amounted  to  about  2%  of  the  entire 
mass. 

In  the  melt  electrodes  of  different  materials  were 
dipped  and  their  surfaces  measured;  anode  and 
cathode  were  always  of  the  same  size.  After  the 
reading  of  the  temperature  the  electrode-potential 
was  obtained  either  by  the  condenser  method,  in 
which  the  condenser  was  discharged  into  a  highly 
sensitive  galvanometer  of  the  Lord  Kelvin  con- 


PROCESSES. 


91 


struction,  or  by  the  compensation  method  with  a 
Lippmann  electrometer  for  the  zero  instrument. 

The  electromotive  force  thus  determined  proved 
to  be  in  the  majority  of  cases  very  small ;  frequently 
in  the  course  of  a  measurement  it  changed  its  sign; 
the  maximum  positive  and  negative  values  are 
given  in  Table  II.  It  may  be  seen  from  this  table 

TABLE  II. 

POTENTIAL  DIFFERENCE  BETWEEN  THE   ELECTRODES   BEFORE 
THE  BEGINNING  OF  THE  ELECTROLYSIS. 


Electrodes. 

Submerged 
Surface, 
Sq.  Cm. 

Temperature, 
Deg.  C. 

Potential 
Difference  E 
between  the 
Electrodes, 
Volts. 

Anode. 

Cathode. 

Copper.  . 

Copper.  . 

104 
104 
8 

2OO 
2OO 
200 

{•         2OO 

824 
824 
920 

824 
824 
824 

824 

j    +0.0025 
(     —0.0019 
<     +  O.OO2 
(      —  O.OO2 
j     +0.0056 
(      -0.0012 

O  .  22 
0.32 
0.25 

(  i-95 
i  1-70 
(  i  •  50 

Copper.  . 

Fresh  carbon 
Platinum.  .  . 

Fresh  carbon 
Iron  

Platinum.  .  .  . 

Polarized  car- 
bon *  

do. 
Fresh  carbon. 
Polarized  car- 
bon   

do. 

Molten  alumi- 
num. ..... 

*  By  polarized  carbon  is  understood  one  that  has  already  served  as  anode 
in  the  normal  electrolysis  of  aluminum  fluoride,  and  is  therefore  loaded  with 
oxygen. 

that  the  electrodes,  in  so  far  as  they  consist  of 
copper,  platinum,  or  fresh  carbon,  do  not  occupy 
the  place  of  some  important  or  constant  electro- 
motive force;  E  even  changes  its  sign;  its  max- 
imum value  in  both  cases  is  about  the  same: 
it  amounts  between  copper-copper .  and  between 


92  PRODUCTION  OF  ALUMINUM. 

copper-fresh  carbon  to  about  0.002  volt;  with 
platinum  it  varies  between  +0.0056  and  —0.0012 
volt. 

If  the  positive  electrode  consists  of  polarized  car- 
bon, the  negative  of  fresh  carbon,  the  electromotive 
force,  which  at  the  beginning  of  the  measurement 
in  the  open  circuit  is  not  inconsiderable,  decreases 
rapidly,  as  soon  as  the  electrodes  are  united  by 
an  external  resistance,  and  is  finally  zero.  If,  on 
the  other  hand,  the  negative  electrode  consists  of 
iron  or  molten  aluminum,  the  positive  of  fresh 
or  polarized  carbon,  the  system  directly  forms  a 
galvanic  element  which  remains  electromotively 
effective  for  some  time  after  the  closing  of  the 
circuit. 

2.  Measurements  during  the  Electrolysis. — These 
were  carried  out  during  four  separate  periods  (a,  b, 
c,  d),  which  were  distinctly  characterized  by  dif- 
ferent current-densities  (current-strengths  per  sq. 
dm) ;  and  they  will  be  described  in  the  following 
pages.  Both  electrodes,  in  these  tests,  consisted  of 
pressed  carbon. 

Period  a. — The  melt  B,  whose  resistance  p  at 
870°  C.  amounted  to  0.024  £>  served  as  electrolyte. 
The  entire  surface  of  each  electrode  was  4.25  sq. 
dm.  Even  with  very  weak  electromotive  forces, 
which  were  delivered  from  an  external  current- 
source,  the  current  which  passed  the  electrolyte  was 
easily  measurable;  after  breaking  the  circuit  the 
two  electrodes  showed  only  a  slight  polarization, 


PROCESSES. 


93 


which  differed  but  little  from  that  measured  before 
the  passage  of  the  current. 

From  the  current-density  o  to  o.oi  amp.  per  sq.  dm, 
E,  the  difference  of  potential  between  the  electrodes. 
is  visibly  proportional  to  the  current-intensity, 
Table  III  gives  the  values  obtained  in  comparison 
with  those  calculated.  In  our  example  E  is  reckoned 
for  the  given  current-densities  according  to  the 
equation 


TABLE  III. 

DIFFERENCE    OF    POTENTIAL    DURING    THE    PERIOD    a. 


Current- 
'  strength, 

Current-density, 

d  =  — 
4-25 

Difference  of  Potential  between  the 
Electrodes,  Volts. 

Obtained. 

Calculated. 

0  .0021 

o  .0055 
o  .0189 
o  .0260 

0.0425 

o  .0005 
o  .0013 
o  .0042 
o  .0060 
o  .0160 

o  .0067 
0.017 

°-°55 
0.077 
0.128 

o  .00651 
0.0171 
O  .0558 
O  .0804 
0-133 

In  explanation  of  the  above  formula,  with  its 
coefficient  k,  unusually  large  in  comparison  with  the 
resistance,  we  may  remark  that  the  latter  is  com- 
posed of  two  terms:  of  p,  the  resistance  of  the 
electrolyte,  and  of  the  term  A/,  which  refers  to  the 
electromotive  force  of  the  polarization.  We  have 


and  therefore 


E-pI+k'I. 


94  PRODUCTION  OF  ALUMINUM. 

Period  b.  —  For  current-densities  from  0.02  to 
2  amp.,  the  difference  of  potential  E  is  no  longer 
proportional  to  the  current-strength,  but  increases 
more  slowly  than  the  current-density.  I  was 
unable  to  obtain  a  general  comparison  between  E 
and  /  for  this  period. 

Period  c.  From  a  current-density  of  2  amp.  per 
sq.  dm  to  100  amp.,  the  values  E  and  /  stand  in 
the  following  relation,  given  according  to  the 
principal  formula: 


This  equation  was  thoroughly  proved  by  experi- 
ments; I  have  found  it  verified  in  a  great  number 
of  baths,  in  which  I  varied  the  dimensions  of  the 
electrodes  and  the  temperature,  while  the  composi- 
tion of  the  bath  was  constantly  maintained. 

I  give  two  examples  below.  The  first  has 
reference  to  the  bath  B,  which  showed  a  small 
percentage  of  silicates  in  its  contents.  The  tem- 
perature during  the  test  was  kept  constantly  at 
870°  C.  The  second  example  refers  to  the  bath  A, 
which  contained  neither  impurities  nor  silicates; 
the  temperature  in  this  case  was  varied  between 
900°  C.  and  noo°C. 

In  the  first  case,  the  original  proportion  of 
silicates,  in  consequence  of  the  electrolysis,  gradually 
diminished,  and  soon  fell  to  zero.  I  could  clearly 
perceive  five  separate  phases;  the  resistance  re- 
mained constant  during  them  all,  being  equal, 


PROCESSES. 


95 


namely,  to  0.024 — a  proof  that  the  percentage  of 
silicate  is  without  effect  upon  this  value.  The 
current-strength  was  kept  during  the  described 
experiment  between  10  and  400  amp.,  correspond- 
ing to  a  current-density  of  2.36  and  94  amp.  per 
sq.  dm. 

From  the  following  table  may  be  seen  the  increase 
of  the  decomposition-voltage  with  the  continuance 
of  the  electrolysis,  for  870°. 

TABLE  IV. 


Phase. 

E  =  e+PI. 

Phase. 

E  =  e+PI. 

I 
2 
3 

I  .33+0.0247 
i  .  50  +o  .0247 

1.75+0.0247 

4 

5 

1.95+0.0247 
2.50+0.0247 

During  the  first  period  e  was  1.33  volts.  As  long 
as  the  melt  still  contained  significant  quantities  of 
silicates,  this  value  of  e  remained  constant,  an  indi- 
cation that  during  this  time  the  work  of  the  current 
is  limited  to  the  dissolution  of  the  silicates.  In  the 
mass,  as  the  proportion  of  silicate  decreased,  e  in- 
creased, and  finally  reached  2.50  volts;  at  this 
stage  scarcely  any  traces  of  impurities  were  still 
found  in  the  electrolyte,  so  that  2.50  volts  may 
be  accepted  for  the  decomposition-voltage  of  the 
aluminum  fluoride. 

In  practice,  one  only  goes  with  the  anode  cur- 
rent-density as  far  as  to  50  amp.  per  sq.  dm,  and 
the  electrodes  are  taken  of  such  dimensions  that  the 
resistance  of  the  bath  is  lessened  in  proportion  as 


96  PRODUCTION  OF  ALUMINUM. 

the  current-strength  utilized  increases,  so  that  the 
current  density  retains  its  value  permanently. 
Thus  the  resistance  of  the  bath  C,  which  was  cal- 
culated for  a  current  of  4000  amp.,  amounted 
merely  to  0.0012  ohm,  in  order  to  obtain  a  cur- 
rent density  of  50  amp.  Since  the  counter-electro- 
motive force  amounted  to  about  2.5  volts,  the  value 
of  E  was  derived  from  the  formula 

E= e-\- pl=  2. 5+ 0.0012.4000=  7.3  volts. 

Likewise  I  found  in  the  bath  B,  with  the  same 
current-density  and  the  current-strength  of  200  amp. 
dependent  thereon,  the  following  value  for  the  differ- 
ence of  potential  E: 

£  =  £4-^7  =  2.5+0.024.200  =  7.3  volts. 

If  the  temperature  was  kept  constant  during 
the  preceding  experiment,  special  measurements 
at  the  bath  A  had  reference  directly  to  the  influ- 
ence of  the  temperature  upon  the  tension  of  the 
cell.  The  melt  A  was  subjected  to  three  different 
temperature-points  of  the  electrolysis,  and  each 
time  p  and  e  were  determined.  That  the  values 
calculated  from  these  quantities  according  to  our 
formula  closely  agree  with  those  experimentally 
determined,  the  following  table  will  show. 

The  entire  surface  of  each  group  of  electrodes 
that  was  sunk  in  the  bath  A  remained  constant 
during  the  three  tests  and  was  equal  to  50  sq.  dm. 


PROCESSES. 
TABLE  V. 


97 


goo°  C. 

1000°  C. 

noo°C. 

E=  2.4  +  O.00447- 

£=2.34  +  0.00337. 

£=2.17+0.00257. 

. 

Difference  in 

. 

Difference  in 

„. 

Difference  in 

4 

Potential,  E. 

4 

Potential,  E. 

| 

Potential,  E. 

£g£ 

Meas- 

Calcu- 

III 

Meas- 

Calcu- 

111 

Meas- 

Calcu- 

g tn<1 

ured, 

lated, 

c  ^<J 

ured, 

lated, 

§  "w*5* 

ured, 

lated, 

O 

Volts. 

Volts. 

0 

Volts. 

Volts. 

0 

Volts. 

Volts. 

196 

3.26 

3-26 

572 

4.23 

4.23 

IS2 

2.48 

2-55 

403 

4.12 

4.17 

650 

•4.48 

4.48 

598 

3-65 

3-67 

485 

5-05 

4-97 

910 

5-30 

5-54 

IOIO 

4.90 

4.48 

885 

6.18 

6-25 

1013 

5-78 

5-74 

143° 

5-74 

5-74 

The  current-density  was  varied  between  the  limits 

=  28.6.    Furthermore,  for 


d  =—  —  =  3.04  and  d  = 
5°  5° 


an  electrode-surface  of  100  dm2  and  a  current- 
density  up  to  40  amp.,  I  found,  in  confirmation 
of  our  fundamental  formula,  a  very  good  agree- 
ment between  the  calculated  and  the  measured 
values  ;  and  this,  indeed,  even  at  a  current-strength 
of  4000  amp. 

Period  d.  —  If  the  current-density  exceeds  100  amp. 
per  sq.  dm,  the  difference  in  potential  at  the  elec- 
trodes may  no  longer  be  expressed  as  a  simple 
function  of  the  values  e  and  /.  It  then  quickly 
attains  the  electromotive  force  of  the  arc,  about 
30  volts  ;  simultaneously  there  is  a  bright  gleam 
of  light  around  the  anode,  and  this  heat-effect  of 
the  current  disappears  only  with  the  falling-off 
in  the  current-density. 


98 


PRODUCTION  OF  ALUMINUM. 


3.  Measurements  after  Breaking  the  Circuit. — If, 
after  breaking  the  circuit,  the  electrodes  are  united 
by  means  of  a  metallic  resistance,  a  polarization- 
current  flows  in  the  outer  closed  circuit,  which  per- 
haps in  the  course  of  an  hour  assumes  a  constant 
value  and  lasts  until  the  melt  has  cooled  down, 
that  is  to  say,  has  hardened. 

Table  VI  refers  to  the  bath  D,  whose  resistance 
was  about  0.0075  ohm.  After  a  current  of  800 
amp.  had  flowed  through  it  for  a  while,  the  latter 
was  suddenly  interrupted,  and  the  cell  at  the  same 
time  closed  by  a  metallic  conductor  whose  resist- 
ance R  was  chosen  about  ten  times  as  large  as  that 
of  the  bath,  so  that 

^  =  10/0  =  0.075  ohm. 

The  decrease  in  potential  E  and  the  current- 
strength  /  in  the  outer  circuit  are  given  in  the 
following  table: 

TABLE  VI. 

DISCHARGE   OP   THE    BATH   D  AFTER   BREAKING  THE    CIRCUIT. 

Exterior  Resistance  R  =0.0 7 5  ohm. 


Minutes  Afterward. 

Difference  in  Potential  E\  . 

Current-strength  , 

/.-  JL. 

0.075 

o 

•95 

25-3 

5 

.88 

25 

15 

.58 

21 

30 

.38 

18.4 

45 

.29 

17.2 

60 

i  .  20 

16 

75 

i  .  20 

16 

PROCESSES. 


99 


TABLE  VII. 

RESISTANCE    p   DURING   THE    DISCHARGE. 


Bath- 

Jfl 

resistance, 

1 

External 
Resistance. 

Potential 
Difference 
EI  and  e\ 

if 
11 

reckoned 
according  to 
the  Formula 

p  Average. 

P  General 
Average. 

£ 

5  w 

P=^—j  —  '• 

Open  circuit 

1.72 

0 

: 

I 

0.075 
0.0125 

1.58 

I  .  10 

21 

88 

0  .0081 
0  .00705 

>•   0.0076 

Open  circuit 

1.72 

0 

Open  circuit 

1.26 

o 

0.0125 

o-795 

64 

o  .0072 

) 

2 

o  .0083 

o-71S 

86 

o  .0063 

>•  o  .0067 

o  .0050 

0.55° 

no 

o  .0065 

1 

Open  circuit 

1.26 

0 

•0.0071 

Open  circuit 

1.17 

0 

3 

0.125 
o  .0050 

o-755 
o  .480 

60  .4 
96 

o  .0068 
o  .0072 

|    0.0070 

Open  circuit 

1.17 

0 

Open  circuit 

0.825 

0 

4 

0.0125 
o  .0050 

o  .  510 

0.343 

40.8 

68.6 

0.0070 

0.0077 

[  0-00735 

Open  circuit 

0.825 

o 

•* 

If  the  current  of  polarization  is  interrupted  for 
an  instant,  in  order  to  close  it  again  immediately, 
and  if  at  each  interruption  one  measures  the  elec- 
tromotive force  e\  between  the  electrodes  with 
the  circuit  open,  one  finds  in  time  a  distinct  lessen- 
ing of  e\.  "The  resistance  p  of  the  electrolyte  may 
be  determined  by  the  formula 


e\  = 


or 


100  PRODUCTION  OF  ALUMINUM. 

and  must  be  identical  with  that  which  is  calcu- 

E  —  e 
lated  by  the  principal  formula,  E  =  e  +  pi,  or  p  —  —^ — . 

Table  VII  refers  to  the  melt  D,  whose  resistance 
during  the  electrolysis  was  found  to  be  0.0075 
ohms.  After  the  breaking  of  the  primary  current 
circuit,  the  electrodes  in  turn  were  short-circuited 
by  resistances  of  0.075,  0.0125,,  0.0083,  and  0.0050 
ohm,  and  the  current-strengths  in  each  one  of 
these  resistances  measured  at  different  times;  fur- 
thermore, the  fall  of  potential  at  the  electrodes 
was  determined  both  with  the  open  (ei)  and  the 
closed  (Ei)  circuit. 

Table  VII  shows  that  the  resistance  of  the  melt  in 
the  periods  of  discharging  and  charging  is  remarkably 
similar  (0.0071  as  contrasted  with  0.0075  ohm). 

Verification  of  the  Faraday-Becquerel  Law.  —  The 
amount  of  aluminum,  which  theoretically  is  sepa- 
rated by  a  coulomb,  amounts  to  0.0936  mg;  the 
ampere-hour  (3600  coulombs)  yields,  therefore, 
0.337  g  of  aluminum.  In  practice,  however,  inas- 
much as  the  negative  electrode  consists  of  carbon, 
scarcely  more  than  80%  of  the  theoretical  value 
is  obtained.  This  is  caused  by  the  fact  that  the 
aluminum,  according  to  the  proportion  of  its  com- 
position, is  partly  reunited  with  the  halogens 
(chlorine,  fluorine)  separated  at  the  positive  elec- 
trode, and  is  thus  retained  in  the  electrolyte. 

If,  however,  iron  cathodes  are  employed  instead 
of  carbons,  the  theoretical  yield  is  easily  obtained; 


PROCESSES.  101 

I  obtained,  for  example,  with  a  current  of  4000 
amp.  during  twenty-two  hours,  that  is  to  say,  then, 
by  means  of  88,000  ampere-hours,  30  kg  aluminum, 
while  the  theoretical  value  was 

P  =88000X0.337  =29656  kg. 

The  aluminum  unites  in  this  case  with  the  cathode- 
metal  to  form  ferro-aluminum,  an  alloy  which  — 
with  a  proportion  of  7%  of  iron  —  is  affected  by 
the  bath  far  less  than  pure  aluminum. 

The  difference  of  potential  with  carbon  cathodes 
amounts  to  7.5,  with  iron  cathodes  to  7  volts. 

In  the  following  statement,  for  both  cases,  the 
electrical  energy  is  calculated  which  is  consumed  by 
a  current  of  4000  amp.  during  twenty-two  hours,  in 
order  to  determine  from  this  and  from  the  quantity 
of  metal  separated  during  this  time  the  expendi- 
ture of  energy  per  kg  aluminum. 

Pure  Aluminum. 

Production  P  during  22  hours:   23.75  kg. 
Electrical  energy  in  horse-power  hours: 


Expenditure  of  electrical  energy  T  per  kg  alumi- 
num: 


102  PRODUCTION  OF  ALUMINUM. 


Ferro-A  luminum. 

Production  P  in  22  hours:   29.656  kg. 
Electrical  energy  in  horse-power  hours 


Expenditure  of  electrical  energy  T  per  kg  alumi- 
num: 

a8HP»>. 


29.656 

Requisite  Nature  of  the  Apparatus.  —  The  crucible, 
which  contains  the  electrolytes,  must  be  so  con- 
stituted that  it  will  not  be  affected  by  the  melt, 
since,  by  any  such  effect,  on  the  one  hand  the 
purity  of  the  aluminum  would  suffer,  on  the  other 
hand  the  crucible  would  soon  become  unfit  for  use. 
From  an  economic  standpoint  also,  if  it  is  desired 
to  obtain  pure  aluminum,  it  is  absolutely  neces- 
sary to  limit  to  a  minimum  the  twofold  attack 
which  the  crucible  suffers  from  heat  and  from 
the  molten  salts,  or,  if  possible,  to  do  away  with  it 
entirely. 

It  is  known  that  impure  aluminum  is  more 
easily  corroded  by  chemical  reagents  than  pure 
metal;  in  addition,  there  is  the  unfavorable  cir- 
cumstance that  while  pure  aluminum  shows  normal 
wear  with  the  effect  of  reagents,  thus  permitting 
the  durability  of  objects  made  of  the  metal  to 


PROCESSES. 


103 


be  approximately  determined  beforehand,  impure 
aluminum  is  so  irregularly  affected  that  it  has  but 
a  limited  usefulness.  The  impurities  of  aluminum 
electrolytically  produced  consist  principally  of  sili- 
con, iron,  and  traces  of  carbon;  while  the  amount 
of  these  was  originally  i%,  at  present  it  hardly 
exceeds  0.15%.  In  this  connection  I  subjoin 
some  very  instructive  analyses: 


1890 

1893 

1898 

0.90% 

0.2t;% 

o  02% 

0.40% 

0.40% 

0     12% 

08.70% 

no  .  7C% 

09.86% 

100.00% 

100.00% 

100.00% 

It  is  seen  that  the  percentage  of  silicon  with 
increasing  perfection  in  apparatus  grows  notably 
less,  so  that  it  finally  becomes  altogether  negli- 
gible, while  the  percentage  of  iron  has  become 
less,  but  yet  remains  always  considerable.  This 
peculiar  phenomenon  depends  upon  the  origin  of 
the  admixtures  mentioned;  for  while  the  silicon 
comes  principally  from  the  melt,  the  various  addi- 
tions and  the  electrode-carbons — and  hence  from 
materials  which  it  is  possible  to  obtain  in  any 
degree  of  purity  desired — the  iron  comes  from  the 
crucible  and  its  armature,  and  may  be  avoided  only 
by  means  of  certain  devices  which  we  shall  now 
proceed  to  describe  more  in  detail. 

Technical    Furnaces. — Of    the    three    furnaces   of 


104  PRODUCTION  OF  ALUMINUM. 

Minet's  construction,  we  shall  describe,  to  begin  with, 
the 

First  Type. — The  apparatus  (Fig.  42)  consists  of 
a  cast-iron  smelting- vessel  VV  of  parallelopipedal 
form,  which  is  externally  protected  by  brickwork 
from  the  attack  of  the  superheated  gases;  for  the 
bath  is  in  this  case  maintained  in  a  molten  state  not 
merely  by  the  current  heat,  but  also  by  artificial 
heat  from  an  external  source  of  warmth.  If  the 
addition  of  warmth  from  without  decreases,  and 
if  the  calories  necessary  for  the  melt  are  furnished 
by  the  current  alone,  the  brick  covering  serves 
principally  for  the  purpose  of  protecting  the  fur- 
nace as  much  as  possible  from  cooling  off  through 
radiation. 

For  electrodes,  carbon  bars  are  employed;  the 
cathode  C  is  constructed  directly  over  a  crucible  cc, 
which  consists  of  the  same  carbon  material  as  the 
cathode,  and  is  for  the  purpose  of  taking  up  the 
aluminum  that  flows  slowly  down  at  the  cathode. 
In  order  to  avoid  any  effect  of  the  bath  upon  the 
melting-vessel,  and  thus  to  prevent  the  melt 
taking  up  iron  salts,  which  would  all  be  more 
easily  decomposed  by  the  current  than  aluminum 
fluoride,  the  crucible  walls  are  connected  to  the 
cathode  as  a  shunt-derived  circuit  with  the  aid  of 
a  resistance  R,  which  is  so  dimensioned  that  through 
it  flows  only  5%  of  the  whole  current.  By  means 
of  this  device  the  inner  walls  of  the  melting- vessel 
are  protected  from  every  attack,  since  along  these 


PROCESSES. 


walls  an  extremely  thin  layer  of  aluminum  is  pre- 
cipitated, which  is  renewed  incessantly.  With  this 
furnace,  which  was  devised  in  the  year  1887,  I 
have  obtained  an  aluminum  which  contains  only 


FIG.  42. 

°-5I%  of  impurities,  namely,  0.33%  of  silicon  and 
0.18%  of  iron. 

Nevertheless  this  apparatus  can  lay  no  claim  to 
technical  utility,  since  the  metal  vessel  V  is  sub- 
ject to  very  rapid  waste,  on  the  one  hand  from 
the  aluminum  which  is  precipitated  upon  its  inner 
surface  and  which  penetrates  the  walls,  while  it 
forms  an  alloy,  ferro-aluminum,  easily  melted  in 
comparison  with  cast  iron;  on  the  other  hand, 
from  the  heating-gases  which  circulate  about  the 
crucible.  The  wasting  is  of  such  a  sort  that  after 


106  PRODUCTION  OF  ALUMINUM. 

an  eight  or  ten  days'  course  the  melt  already 
trickles  through,  and  the  vessel  must  be  permanently 
set  aside. 

Second  Type. — In  this  furnace  the  melt  is  brought 
about  solely  by  the  current  heat.  The  crucible 
consists  of  metal,  and  is  likewise  of  parallelopipedal 
form.  It  is  lined  inwardly  by  a  layer  of  carbon, 
which  serves  as  negative  electrode  (Fig.  43).  The 
anode  consists  of  one  or  more  blocks  of  carbon, 
which  are  arranged  in  the  middle  of  the  crucible. 

At  the  beginning  of  the  operation  the  percentage 
of  iron  separated  is  very  small;  it  may  sink  to  o.i- 
0.2%,  since  the  crucible  material  (usually  cast 


FIG.  43. 

iron)  in  consequence  of  the  lining  we  have  men- 
tioned does  not  at  first  come  in  contact  with  the 
melt.  At  the  high  temperature,  however,  to  which 
the  carbon  mantle  is  brought  (750-850°  C.),  this 
soon  becomes  porous,  allows  the  melt  to  trickle 


PROCESSES.  107 

through,  and  as  quickly  brings  about  a  contact 
between  the  bath  and  the  metal  crucible.  From 
this  moment  the  latter  is  in  electrolytic  connection 
with  the  anode  A,  and  in  consequence  aluminum 
is  separated  thereat,  and  in  addition  sodium, 
which,  on  account  of  the  considerable  propor- 
tion of  sodium  chloride  in  the  bath,  is  precipi- 
tated simultaneously  with  aluminum,  provided 
the  electromotive  force  at  the  electrodes  exceeds 
the  decomposition- voltage  of  common  salt,  4.35 
volts. 

If  the  sodium  is  separated  exclusively  at  the 
surface  of  the  carbon  covering  CC,  this  brings 
with  it  no  further  disadvantage.,  The  metallic 
sodium  reduces  the  aluminum  fluoride  coming  into 
contact  with  it,  and  thus  frees  an  equivalent  quantity 
of  aluminum.  If,  however,  the  sodium  is  formed 
in  the  pores  between  the  wall  of  the  crucible  and 
the  carbon  mantle,  in  its  immediate  neighborhood 
there  is  not  found  a  sufficient  quantity  of  aluminum 
fluoride  to  exchange  with  the  sodium  to  form 
sodium  fluoride  and  aluminum.  Hence  the  sodium 
penetrates  into  the  mass  of  carbon  saturated  with 
aluminum  fluoride,  corrodes  it,  and  reduces  it 
finally  to  powder. 

The  separated  aluminum  is  assembled  at  the 
bottom  of  the  crucible,  and  is  drawn  off  through 
the  tapping-vent  /.  At  first  almost  free  from  all 
impurities,  it  becomes  ferruginous  with  continued 
operation.  Many  apparatus  of  this  type  keep  in 


io8 


PRODUCTION  OF  ALUMINUM. 


condition  for  thirty  to  forty  days;  others  become 
almost  immediately  useless. 

If  the  aluminum  is  destined  for  alloys,  this  fur- 
nace may  be  employed  to  advantage  industrially, 
at  least  in  this  way:  by  making  the  crucible  of 
that  metal,  or  of  one  of  those  metals,  entering  into 
the  alloy.  The  absorption  of  the  crucible  material 
into  the  melt  during  the  electrolysis  in  this  case, 
of  course,  is  attended  by  no  inconveniences. 

Third  Type. — This  stands  midway  between  the 
first  type  and  the  second.  The  addition  of  heat  is 
provided  for  entirely  by  means  of  the  current. 
The  metal  crucible  (Fig.  44)  is  also  in  this  case 


FIG.  44. 

enveloped  in  a  carbon  covering,  the  strength  of 
which,  however,  is  far  more  significant  than  in 
the  case  of  the  preceding  furnace ;  and  the  covering 


PROCESSES.  109 

is  entirely  independent  of  the  electrodes.  The 
aluminum  flows  away  along  the  cathode  C  and  is 
collected  in  a  basin  which  is  set  in  the  middle  of 
the  bottom  of  the  crucible.  From  this  basin  the 
metal  may  be  drawn  off  through  the  channel  /. 

Since  in  this  apparatus  the  covering  does  not 
take  the  place  of  an  electrolytic  process,  it  gains, 
to  an  unusual  extent,  in  durability  and  constancy. 
The  same  thing  is  true  also  of  the  metal  crucible 
wall,  which  may  be  cooled  in  such  a  way  that  the 
temperature  of  its  inner  surface  remains  lower  than 
that  of  the  melt,  so  that  the  latter  cannot  penetrate 
so  far  as  to  the  walls  of  the  crucible.  Since,  further- 
more, there  is  no  sort  of  electrolytic  connection  be- 
tween crucible  and  anode,  the  melt  remains  free 
from  a  percentage  of  iron,  and  we  at  once  have 
the  condition  for  the  production  of  very  pure  alu- 
minum. 

If  aluminum  is  to  be  used  for  alloys,  the  crucible 
may,  as  in  the  case  of  the  second  type  of  furnace, 
be  made  suitably  of  one  of  the  metals  with  which 
the  aluminum  is  to  be  alloyed. 

Furthermore,  with  a  heavy  lining  and  thorough 
cooling  from  without,  the  temperature  may  be 
lowered  to  below  500°  C.,  while  that  of  the  melt 
amounts  to  about  75o°C. ;  under  these  conditions 
it  is  very  easily  possible  to  make  the  crucible  of 
aluminum,  so  that  one  is  able  to  obtain  a  metal 
which  for  its  sole  impurity  shows,  at  most,  traces 
of  silicon. 


HO  PRODUCTION  OF  ALUMINUM. 

The  space  occupied  by  the  furnace  is  not  much 
greater  in  the  case  of  the  third  type  than  in  that 
of  the  second.  If,  in  order  to  avoid  certain  phenom- 
ena of  heat,  the  anodes  are  of  such  dimensions  that 
only  a  current  of  50  amp.  per  dm2  of  surface  passes 
through,  there  is  free  play,  at  least  in  so  far  as  the 
cathode  is  concerned — though  the  current-density 
must  not  be  so  great  that  there  is  an  excessive 
heating  of  the  cathode;  the  current-density  at 
the  negative  electrode  may  be  something  like  ten 
times  as  great  as  at  the  positive,  amounting,  there- 
fore, to  about  500  amp.  per  dm2.  We  see  that  the 
construction  of  the  cathode  demands  no  consider- 
able increase  of  volume  for  the  third  type  in 
comparison  with  the  second. 

It  should  be  remarked,  also,  that  the  cathode 
remains  for  a  long  time  capable  of  being  used; 
frequently  I  have  had  cathodes  in  use  for  eight 
days  before  they  required  to  be  renewed.  The 
anodes,  on  the  other  hand,  must  usually  be  renewed 
twice  a  day;  still,  this  is  no  more  true  of  the  fur- 
nace of  the  third  type  than  in  the  case  of  that  of 
the  second  type;  so  that  the  last-described  con- 
struction unites  in  itself  all  the  requirements  of  an 
industrial  apparatus. 

Technical  Data. — If  an  external  source  of  heat 
is  employed,  in  order  to  keep  the  bath  in  a  molten 
state — this  is  true  only  of  the  first  and  second 
types — the  difference  in  potential  at  the  electrodes 
amounts  to  5-6  volts;  if,  however,  the  operation 


PROCESSES. 


Ill 


is  carried  on  without  an  addition  of  heat  from  the 
exterior,  the  electromotive  force  varies  between 
7  and  8  volts. 

Table   VIII    gives   the   electrolytic   data   within 
further  current-variations. 

TABLE  VIII. 


Date  of 
the  Test. 

Constitu- 
tion of  the 
Cathode. 

Dura- 
tion of 
the  Test 
in  Hours 

Current- 
inten- 
sity in 
Amperes 

Differ- 
ence of 
Poten- 
tial at 
the  Elec- 
trodes in 
Volts. 

Weight  of  the 
Metal  Separated 
off  in  Grams, 

Effi- 
ciency 
P 

Obtain'  dlTheoret. 

*       \       P 

*-> 

The  addition  of  heat  is  partially  the  consequence  of  heating 

from  without.  First  type  of  furnace. 

1887 

May   7 

carbon 

15 

89 

5-5 

250 

455 

55% 

July  13 

" 

14 

90 

4 

260 

428 

60% 

Sept.  27 

iron 

23 

IOO 

5-5 

400 

782 

51  % 

Nov.  26 

carbon 

12 

142 

5-75 

•  380 

579 

75% 

1888 

Feb.  4 

carbon 

13 

1  80 

6 

500 

796 

62% 

Aug.  4 

11 

12 

360 

6 

IOOO 

1460 

68% 

1889 

Sept.  30 

carbon 

20 

7OO 

5-6 

2600 

4760 

54% 

Nov.  20 

" 

20 

800 

5-6 

2800 

5440 

52% 

Dec.   5 

iron 

20 

800 

5-5 

3600 

5440 

66% 

1890 

Jan.  20 

iron 

7 

975 

6.1 

1900 

2320 

82% 

Dec.  10 

carbon 

22 

1500 

5-55 

6500 

II22O 

58% 

The  addition  of  heat  is  entirely  the  consequence  of  the 

work  of  the  current.  Second  type  of  furnace. 

1892  | 

carbon 
iron 

24 
24 

3000 
3000 

8.25 

7-75 

16157 

20074 

24480 
24480 

66% 

82% 

T  Qr\  -•>   J 

carbon 

24 

35oo 

8.25 

19421 

28560 

68% 

J°93  | 

iron 

24 

35°° 

7-75 

24276 

28560 

85% 

T  8r>  A   J 

carbon 

24 

4000 

8.25 

22848 

32640 

70% 

I»94  -j 

iron 

24 

4000 

7-75 

29376 

32640 

90% 

In  all  these  tests  the  difference  of  potential  at 
the   electrodes  was    kept    approximately  constant 


112  PRODUCTION  OF  ALUMINUM. 

by  means  of  corresponding  alterations  in  the  fur- 
nace- and  electrode-dimensions.  With  a  current- 
interval  of  89-1500  amp.,  in  the  case  of  the  first 
type  of  furnace — during  the  simultaneous  partial 
employment  of  an  external  source  of  heat — the 
electromotive  force  varied  between  4.55  and  6.35 
volts,  the  efficiency  <£  between  52  and  75%  in 
proportion  as  carbon  cathodes  were  used,  and 
between  51  and  82%  in  proportion  as  iron  elec- 
trodes were  used.  With  the  second  type  the  elec- 
tromotive force  during  a  current-interval  amounted 
to  from  3000-4000  amp.,  and  with  the  avoidance 
of  any  external  heating  to  8.55  volts  with  car- 
bon cathodes  and  7.75  volts  with  iron  cathodes — 
hence  with  an  unlined  furnace-chamber — while 
the  efficiency  reached  in  the  first  case  70%,  in  the 
second  90%,  of  the  theoretical  value. 

Expenditure  of  Energy  per  Kg  Aluminum.  —  First 
type  of  furnace;  a  portion  of  the  necessary  heat 
being  taken  from  an  exterior  heat-source. 

Carbon  Cathodes. 

November  26,  1887. 35  horse-power 

December  10,  1890 40 

Iron  Cathodes. 

December  5,  1889 33  horse-power 

January  20,  1890 30 

Second  type  of  furnace;   the  heat  is  exclusively 
caused  by  the  current. 


PROCESSES.  113 

1894. 

Carbon  cathode 42.5  horse-power 

Iron  cathode 30.5 

If  we  draw  the  inference  from  what  has  been  said, 
we  see  that  the  expenditure  of  energy  for  the  two 
furnaces  is  about  the  same;  it  increases  slowly, 
however,  with  increasing  strength  of  current. 

He*roult  Process. 

The  various  furnace-constructions  of  this  inves- 
tigator we  have  already  described  (see  pages  30-32). 
As  for  the  electrolytes,  Heroult  employs  a  melt  of 
aluminum-sodium  double  fluoride  (cryolite)  without 
any  addition  whatever  of  a  salt  of  the  alkalis  or 
alkaline  earths.  The  aluminum-salt  decomposed  by 
the  electrolysis  is  replaced  by  anhydrous  alumina 
which  is  added  to  the  melt  during  the  operation, 
mixed  with  some  parts  of  cryolite. 

At  the  Metallurgical  Congress  which  was  held  at 
Paris  during  the  World's  Fair  of  1900,  in  a  debate 
on  the  subject  of  the  production  of  aluminum, 
Heroult  took  the  floor  in  order  to  make  a  commu- 
nication regarding  his  first  researches,  after  some 
consideration  of  the  historical  aspect  of  the  subject. 
I  will  give  the  description  of  this  portion  of  his 
achievements  in  his  own  words: 

"We  may  say  that  the  first  thought  of  a  tech- 
nically practicable  process  for  the  electrometallur- 
gical  production  of  aluminum  originates  from  the 
year  1886.  Bunsen's  and  Deville's  successful  at- 


114  PRODUCTION  OF  ALUMINUM. 

tempts  in  the  electrolytic  decomposition  of  alu- 
minum chloride  had  made  a  profound  impres- 
sion; thanks  to  the  labors  of  Favre  and  Silber- 
mann  and  to  the  researches  of  Berthelot,  there 
were  also  at  hand,  even  at  that  time,  very  reliable 
thermochemical  data;  and  hence  it  needed  but  a 
step — for  we  have  already  reached  a  period  sub- 
sequent to  the  invention  of  the  dynamo-machine — 
in  order  to  arrive  at  the  point  where  we  stand 
to-day;  although,  to  be  sure,  the  original  materials 
for  the  manufacture  of  aluminum — alumina  and 
cryolite — were  already  universally  known. 

"  In  view  of  these  considerations,  I  became 
convinced  that  the  electrolytic  production  of  alumi- 
num was  only  a  question  of  time.  I  next  attempted 
such  a  production  with  aqueous  solutions;  since, 
however,  these  experiments  all  resulted  in  failure, 
I  passed  immediately  to  the  electrolysis  of  molten 
halogen-salts. 

"  We  must  not  forget  that  the  electrical  industry 
was  then  only  in  the  first  stage  of  its  development. 
To  procure  carbons  having  a  diameter  greater  than 
50  mm  was  at  that  time  not  yet  possible.  The 
few  crucibles  available  in  laboratories  and  factories 
were  produced  by  hollowing  out  rotating  retort- 
carbon. 

"  After  countless  failures,  I  once  observed  that  in 
an  attempt  to  electrolyze  melted  cryolite  the  iron 
cathode  became  fissured,  allowing  the  contents  of  the 
crucible  to  flow  out.  Considering  the  temperature 


PROCESSES.  115 

with  which. I  then  worked,  and  the  current,  which  I 
took  from  some  Bunsen  elements,  I  could  not  under- 
stand how  it  was  that  iron  should  melt  under  these 
circumstances.  A  careful  investigation  of  the  re- 
mains of  the  cathode  led  me  to  suppose  that  an 
alloy  might  have  formed,  and  when,  some  days 
thereafter,  I  sought  to  lower  the  temperature  of 
the  electrolyte  by  the  addition  of  aluminum- 
sodium  double  chloride,  I  was  able,  to  my  surprise, 
to  state  it  as  a  fact  that  the  carbon  anode  gave 
clear  indications  of  having  been  attacked.  I  con- 
cluded from  this  that  "an  oxide  was  here  operating, 
the  reduction  of  which  must  have  taken  place  at 
the  expense  of  the  anode.  I  verified  this  conjecture, 
and  found  it  was  actually  so — that  the  aluminum- 
sodium  double  chloride  contained  considerable 
quantities  of  alumina,  which  originated  from  the 
dissolution  of  the  chloride  brought  about  by  mois- 
ture. The  way  was  now  indicated  by  which  a 
technically  practicable  aluminum-process  might  be 
obtained.  The  matter  was  always  more  difficult 
than  one  would  suppose;  I  will,  however,  pass 
lightly  over  the  details  of  further  attempts,  which 
do  not  radically  differ. 

"  My  practical  knowledge  of  chemistry  was  at 
the  time  that  of  a  student  of  twenty-three;  of 
special  knowledge  I  had  as  good  as  none  at  all. 
Under  these  circumstances,  it  is  needless  to  say 
that  after  I  had  taken  out  my  first  patent  I  sought 
the  counsel  and  encouragement  of  those  men  who 


Ii6  PRODUCTION   OF  ALUMINUM. 

were  then  considered  authorities  on  this  subject. 
Pechiney  (Salindre),  whom  I  first  approached, 
explained  to  me  that  aluminum  was  a  metal  of 
restricted  usefulness;  at  most,  it  might  be  used  for 
opera-glasses;  and  whether  I  wanted  to  sell  the 
kilogram  for  10  or  100  francs,  I  would  not  be  able 
to  dispose  of  one  kilogram  more.  It  was  otherwise 
in  the  case  of  aluminum  bronze,  of  which  con- 
siderable quantities  were  handled  commercially,  if 
I  could  produce  it  cheaply;  1  would  then,  beyond 
a  doubt,  come  out  even  in  my  reckoning. 

"  I  had  already  in  this  Connection  undertaken 
some  successful  experiments;  and  I  therefore  laid 
aside  for  the  time  being  the  production  of  pure 
aluminum  and  turned  to  a  series  of  new  researches, 
which  in  the  year  1887  ^Qd  "to  a  second  patent, 

"  In  this  additional  patent  a  system  of  electric 
furnaces  and  a  process  were  described  which  made 
possible  a  continuous  production  of  alloys  of  alumi- 
num, and  particularly  of  all  metals  difficult  to  melt 
and  reduce. 

11  Although  in  point  of  time  the  electric  furnaces 
of  Siemens  and  Cowles  anticipated  my  invention, 
my  furnace  had  yet  other  special  features,  such 
as  the  tapping- vent,  etc.,  which  passed  into  universal 
electrometallurgical  use.  I  will  only  mention  that, 
for  example,  all  carbide  factories  have  introduced 
carbon  crucibles  with  a  movable  electrode  and  a 
tapping-vent. 

"  When    my    investigations    had    reached    this 


PROCESSES.  II? 

stage,  I  went  to  Switzerland,  where  I  concerned 
myself  for  a  year  almost  exclusively  with  aluminum 
bronze.  I  soon  saw,  however,  that  the  difficulty 
lay  not  herein,  but  in  the  production  of  pure  alumi- 
num, and  so,  in  conjunction  with  Dr.  Kiliani,  I 
took  up  again  the  process  of  1886. 

"  I  may  here  be  permitted  to  state  my  attitude 
with  regard  to  the  vexed  question  of  the  theory  of 
the  reaction.  Several  investigators  are  of  the 
opinion  that  the  electrolysis  does  not  consist  in 
the  dissolution  of  the  alumina,  in  contradiction  to 
my  patent,  in  which  I  expressly  speak  of  the  elec- 
trolysis of  the  alumina.  I  have  been  able  to  demon- 
strate that  the  alumina  may  be  electrolyzed,  since 
I  succeeded  in  fusing  it  in  the  arc  and  in  decompos- 
ing it  by  the  continuous  passage  of  the  current. 

11  It  is  true  that  I  obtained  only  a  slight  yield 
of  metal  (some  hundred  grams) ;  still,  every  error 
in  this  connection  is  excluded,  and  we  must,  there- 
fore, of  necessity  infer  that  in  my  experiments 
simply  the  electrolysis  of  alumina  has  taken  place. 
In  fact,  if  we  dissolve  pure  cryolite  by  means  of 
the  current  we  obtain  pure  aluminum,  not,  how- 
ever, fluorine  also.  The  latter,  with  sodium  fluoride, 
which,  indeed,  is  present  in  excess  in  consequence 
of  the  decomposition  of  the  aluminum  fluoride, 
forms  a  composition  which  is  still  constant  at  the 
temperature  concerned.  This  may  be  demonstrated 
by  grinding  the  cooled  mass  and  digesting  it  with 
water.  There  is  thus  obtained  an  mdissoluble 


Ii8  PRODUCTION  OF  ALUMINUM. 

portion,  which  shows  all  the  peculiarities  and  the 
composition  of  cryolite,  and  a  soluble  part,  which  is 
nothing  but  acid  sodium  fluoride.  If,  however, 
the  operation  is  .carried  on  at  a  higher  temperature, 
one  does  not  obtain  aluminum,  but  sodium,  which 
develops  in  abundant  vapors. 

"  From  these  experiments  we  must  reach  the 
conclusion  that  sodium  primarily  is  separated  at 
the  cathode  through  the  electrolysis,  which  then  in 
its  turn  reduces  aluminum  fluoride  in  a  molten 
state.  In  this  case,  therefore,  we  have  only  alumi- 
num at  the  cathode.  If  the  temperature,  on  the 
other  hand,  is  increased,  sodium-vapors  are  de- 
veloped at  the  negative  electrode,  and  the  reduc- 
tion of  aluminum  fluoride  does  not  take  place. 
On  the  basis  of  this  hypothesis,  the  role  of  the 
alumina  may  easily  be  explained.  We  have,  on 
the  one  hand,  a  molten  compound,  which  contains 
fluorine  in  excess;  on  the  other  hand,  alumina  and 
carbon.  If  now  the  heats  of  formation  of  alumina 
and  aluminum  fluoride  are  of  a  like  magnitude, 
we  have  in  favor  of  the  transposition  of  the  oxide 
the  circumstance  that  oxygen  is  freed  hereby, 
which,  as  soon  as  it  comes  into  contact  with  the 
anode,  attacks  the  latter." 

Use  of  the  Eteroult  Patents.  —  Heroult  establish- 
ments are  found  in  France,  Switzerland,  Germany, 
Austria,  and  England.  In  France  is  the  "  Societe 
Electrom6tallurgique  Franchise,"  which  turns  to 
account  the  Heroult  process.  This  society  was 


PROCESSES.  H9 

founded  by  Gustave  Munerel,  and  has  notably 
developed  under  the  direction  of  Emile  Vielhomme. 
In  Paris  M.  Dreyfus  is  its  representative.  The 
director  of  the  establishment  in  La  Praz  is  Victor 
Arnould.  The  society  possesses  two  factories  with 
water-power,  one  in  Froges  (Isere),  the  other  in  La 
Praz  (Savoy).  In  both  establishments  carbon 
electrodes  and  electrolytic  aluminum  are  produced. 
It  also  possesses  a  factory  for  chemical  products  in 
Gardannes  (Bouches  du  Rhone),  where  alumina  is 
produced. 

For  Switzerland,  Germany,  and  Austria  the 
Heroult  patents  are  in  the  possession  of  the  Alumi- 
nium-Industrie-Aktien-Gesellschaft  at  Neuhausen, 
which  in  Neuhausen  (Switzerland),  in  Rheinfelden 
(Baden),  and  in  Lend-Gastein  (Austria)  operates  ac- 
cording to  this  process.  The  company  obtains  its 
alumina  from  the  Bergius  factory  in  Silesia. 

In  England  it  is  the  British  Aluminum  Company 
which  has  obtained  the  license  for  the  Heroult 
patents.  To  it  belongs  an  establishment  (water- 
power)  in  Foyers  (Scotland),  and  an  alumina 
factory  in  Larne-Harbour  (Ireland) ;  also  factories 
in  Greenock  and  Milton-on-Trent,  where  electrodes 
and  aluminum  plates  are  made. 

Among  the  persons  who  in  a  technical  or  a  financial 
way  have  promoted  the  work  of  Heroult  may  be 
mentioned:  Gustave  Naville,  superintendent  of 
Escher  Wyss,  and  Colonel  Huber  of  the  Oerlikon 
machine  factory,  who  together  established  the 


120  PRODUCTION  OF  ALUMINUM. 

Schweizerische  Metallurgische  Gesellschaft,  and  have 
erected  the  first  aluminum  factory  in  Switzerland 
(Neuhausen,  near  ScharThausen) ;  also  Dr.  Kiliani, 
Frei  of  Neuhausen,  and  factory-superintendent 
Schindler. 

The  English  company  was  founded  by  Ristori, 
with  support  on  the  part  of  Sir  William  Thomson 
(later  Lord  Kelvin). 

C.  M.  Hall  Process. 

This  process  resembles  both  of  the  preceding  ones. 
In  contradistinction  to  the  Heroult  patent,  the 
aluminum-sodium  double  fluoride  is  not  added  in  its 
pure  state,  but,  as  in  the  Minet  process,  mixed  with 
changing  quantities  of  salts  of  the  alkalis  and 
alkaline  earths.  As  admixtures  we  have  to  take 
into  account  the  chlorides  of  potassium,  sodium, 
lithium,  and  the  fluorides  of  sodium,  lithium,  or 
calcium.  These  various  admixtures  are  for  the  pur- 
pose of  keeping  down  the  melting-temperature  of 
the  electrolyte,  in  order  to  maintain  an  easily 
flowing  bath  at  a  lower  temperature.* 

Hall  has  constructed  a  great  number  of  apparatus, 
which  may  be  divided  into  three  general  groups. 
Fig.  45  presents  the  vertical  section,  Fig.  46  the 
complete  view  of  a  furnace  of  the  first  type,  in 
which,  according  to  the  statement  of  the  inventor, 
aluminum  is  to  be  produced  by  the  electrolysis  of 

*  American  Patent  of  July  9,  1886.  American  Patents  400766 
and  400664  of  April  2,  1889. 


PROCESSES. 


121 


a,  solution  of  alumina  in  sodium-  (or  potassium-) 
aluminum  double  fluoride. 


FIG.  45- 


FIG.  46. 


The  electrodes  C  and  D  are  of  carbon;  the 
vessel  AA,  which  contains  the  electrolyte,  consists 
of  clay  or  < steel ;  it  is  lined  within  by  a  layer  of  car- 
bon, which  protects  it  against  the  corroding  attack 
of  the  molten  alumina. 

Figures  47  and  48  reproduce  two  other  furnace 
types  of  the  Hall  construction;  in  Fig.  47  both 
electrodes  are  separated  by  a  partition;  in  Fig.  48 
this  is  not  the  case. 

In  a  third  group  of  Hall  furnaces  the  melting- 
vessel  forms  at  the  same  time  one  of  the  elec- 
trodes (Figs.  49  and  50). 

All  these  apparatus  were  originally  arranged  for 


122 


PRODUCTION  OF  ALUMINUM. 


external  heating;  so  far  as  I  am  aware,  however, 
the  arrangement  has  of  late  years  been  abandoned. 


FIG.  47- 


FIG.  48. 


FIG.  49. 


FIG.  50. 


The  Hall  process  is  employed  in  Pittsburg,  Penn., 
and  in  Saint-Michel-de-Maurienne,  France. 

In  the  following  pages  several  additional  processes 
will  be  cited,  which,  it  is  true,  have  not  been  em- 
ployed industrially,  but  which — particularly  as 


PROCESSES.  123 

regards  the  arrangement  of  separate  details  of 
the  apparatus — are  not  without  interest. 

J.  B.  Hall  Process. — The  iron  crucible  is  here  lined 
on  the  inside  with  carbon,  and  serves  as  the  cathode. 
For  the  electrolyte  a  melt  of  the  chlorides  of  alu- 
minum, sodium,  and  lithium  is  employed.  The 
aluminif erous  anode  placed  in  the  middle  of  the 
apparatus  provides  for  the  renewal  of  the  alumina. 

Berg  Process. — A  mixture  of  aluminum  ore  (for 
example,  cryolite  and  bauxite),  carbon  and  alkali 
nitrate  (or  alkali  sulphide)  is  electrolyzed  at  a  low 
temperature.  The  nitrate  or  sulphide  is  to  bring 
about  the  separation  of  the  aluminum  created  from 
the  alumina  by  reduction  with  carbon,  from  the 
accompanying  impurities,  iron,  silicon,  etc.,  which 
latter  arise  from  the  matrix  of  the  ore  or  from  the 
crucible  material.  The  less  oxidizable  aluminum 
is  not  affected  thereby. 

Bull  Process  (Fig.  51). — A  and  B  are  two  graph- 
ite crucibles,  connected  one  behind  the  other,  which 
are  heated  by  means  of  a  gas-firing.  In  the  crucible 
A  common  salt  or  chloride  of  potassium  is  melted, 
in  B  aluminum  chloride  is  volatilized.  The  melt 
is  subjected  to  electrolysis  in  crucible  A,  wherein 
the  positive  electrode  is  formed  by  the  crucible 
walls,  the  negative  by  the  graphite  rods  EE. 

The  course  of  the  operation  is  as  follows :  Under 
the  effect  of  the  current,  sodium  is  formed  in  cruci- 
ble A,  upon  which  the  aluminum-chloride  vapors 
arising  from  B  are  allowed  to  react.  The  reaction 


124 


PRODUCTION  OF  ALUMINUM. 


is  very  lively;  the  aluminum  is  assembled  at  the 
bottom  of  the  crucible  over  a  layer  of  pure  alu- 
mina a',  and  is  in  this  way  protected  from  the  effect 
of  the  chlorine  vapors  developing  only  at  the  upper 
portion  of  the  crucible  walls.  The  metal  is  drawn 
off  every  four  or  five  days;  the  chlorine  is  con- 


FIG.  51. 

ducted  by  means  of  a  peculiar  tube,  seen  in  the 
illustration,  into  a  collecting-tube  in  which  a  jet 
of  steam  maintains  the  circulation. 

In  order  to  force  the  aluminum  chloride  vapors 
from  B  to  A  and  to  accelerate  their  reduction,  a 
jet  of  hydrogen  is  introduced  at  //,  which  is  gen- 
erated by  passing  water-vapor  over  sodium  and 
thus  decomposing  it.  From  this  point  the  opera- 
tion is  so  carried  on  that  in  the  crucible  A  more 
sodium  is  formed  than  is  necessary  for  the  decom- 
position of  the  chloride  of  aluminum  coming  from  B. 
The  sodium- vapors  are  conducted  through  the  tube 
G  to  7,  where  they  are  condensed. 


PROCESSES. 


125 


Daniel  Process.  —  This  process  differs  from 
Deville's  only  in  the  respect  that  here,  in  conse- 
quence of  the  regeneration  of 
the  aluminum-sodium  double 
salt,  a  continuous  operation  is 
provided  for.  Fig.  52  gives  the 
details  of  the  crucible  which 
contains  the  molten  aluminum 
chloride,  Fig.  53  the  entire 
view.  The  crucibles  B,  which 
are  charged  with  the  aluminum 


FIG.  53. 

salt,  have  the  form  of  iron  troughs,  and  are  heated 
by  flame-gases  (A)\  in  each  of  them  a  series  of  cells 
is  suspended,  in  which  the  carbon  anodes  and  the 
metal  cathodes  are  placed,  which  latter  consist  for 
the  most  part  of  aluminum,  and  are  separated  from 


126  PRODUCTION  OP  ALUMINUM. 

the  anodes  by  the  porcelain  cylinders  G.  In  the 
electrolysis  the  aluminum  is  separated  at  the 
cathode,  while  the  chlorine  developing  at  the 
anode,  mixed  with  the  vapor  of  chloride  of  alu- 
minum, escapes  through  the  tube  g,  in  order  first 
to  stream  into  the  columnar  apparatus  C\D±.  The 
latter  consists  of  a  number  of  compartments, 
which  are  charged  with  a  composition  of  alumina 
and  dry,  large-grained  carbon.  The  chlorine 
changes  the  alumina  into  chloride,  which,  brought 
back  into  the  bath  B,  there,  with  the  excessive 
sodium  chloride,  rebuilds  the  double  salt.  The 
third  column,  EI,  is  merely  for  the  purpose  of  pre- 
viously drying  the  alumina  and  carbon  intended 
for  the  other  two  columns,  C\  and  DI.  The  heat- 
ing of  the  columnar  apparatus  is  effected  by  fire- 
gases,  whose  current  is  regulated  by  means  of  a 
steam-injector.  The  screw-mover  b  provides  for  the 
thorough  mixing  of  the  melt  during  the  elec- 
trolysis. 

Dhiel  Process. — -Alum,  sodium  fluoride,  calcium 
chloride  or  magnesium  chloride,  and  sodium  sul- 
phate are  mixed  in  a  sufficient  quantity  to  obtain, 
through  a  double  transposition,  aluminum-sodium 
double  fluoride  and  alkali  sulphates,  which  latter 
are  separated  by  washing.  The  fluoride  is  melted 
with  sodium  chloride  and  fluor-spar,  and  the  molten 
mass  subjected  to  the  electrolysis. 

Fig.  54  represents  the  crucible,  as  used  espe- 
cially by  Dhiel.  The  anode  F  consists  of  carbon; 


PROCESSES. 


127 


if  one  desires  to  obtain  pure  aluminum,  carbon  is 
also  employed  for  the  cathode;  otherwise  copper 
or  iron  is  used,  according  to  the  alloy  which  is 


FIG.  54. 

to  be  produced,  c  is  a  partition  which  separates 
the  two  electrodes. 

Douglas-Dixon  Process.  —  This  patent  is  exactly 
like  Bull's,  with  the  single  difference  that  mag- 
nesium is  employed  as  reducing-metal.  A  com- 
position of  35  parts  MgCl2,  25  parts  KC1,  40  parts 
NaCl,  mixed  with  3-5%  aluminum-sodium  double 
fluoride,  is  electrolyzed. .  Before  the  electrolysis 
the  mixture  is  heated  in  a  melting-crucible  to 
about  800°  C. 

The  tension  of  the  electrodes  amounts  to  7-8  volts. 
MgCl2  is  decomposed  into  magnesium,  which  rises 
to  the  surface  of  the  melt,  and  into  chlorine,  which 
escapes  through  openings  let  into  the  top  of  the 
crucible  and  streams  into  a  retort  in  which  is  found 


128  PRODUCTION   OF  ALUMINUM. 

a  mixture  of  alumina,  carbon,  and  common  salt. 
The  alumina  is  dissolved  by  chlorine  with  the 
formation  of  aluminum  chloride,  which  unites  with 
sodium  chloride  to  form  a  double  salt.  The  reac- 
tion is  expressed  in  the  equation 

3C  +  6C1  +  A12O3  +  6NaCl  =  A12C16. 6NaCl  +  3CO. 

The  temperature  is  kept  sufficiently  high  to 
melt  the  chloride  without  volatilizing  it.  When  it 
has  arrived  at  this  state  in  the  crucible,  it  is  reduced 
by  the  magnesium  floating  upon  the  surface  of  the 
bath,  according  to  the  equation 

Al2Cl6.6NaCl  +  3Mg  =  2  Al  +  3MgCl2  +  6NaCl 

with  a  simultaneous  regeneration  of  magnesium 
chloride,  which  remains  in  the  melt.  In  Fig.  55 
diagram  a  shows  the  apparatus  as  employed  in 
the  process.  The  graphite  crucible  A  stands  upon 
a,  grate  directly  under  the  retort  B.  This  communi- 
cates with  a  condenser,  which  takes  up  the  carbonic 
oxide  and  the  volatile  chloride  developing. 

A  modified  arrangement  is  seen  in  b.  While  in 
the  former  instance  the  crucible  was  at  the  same 
time  the  cathode,  here  such  is  not  the  case.  The 
pin  a  is  here  the  negative  electrode.  The  retort 
stands  at  the  side  of  the  crucible,  and  is  united 
with  it  by  means  of  the  tube  a'. 

At  c  the  mixture-  of  alumina  and  carbon  is  sep- 
arated from  the  reducing-bath  only  by  the  porous 
partition-wall  m,  so  that  the  aluminum  chloride, 


PROCESSES. 


129 


which  is  formed  by  the  chlorine  developed  at  the 

anode,  is  directly  reduced  at  the  surface  of  the  bath. 

The  process  of  reduction  by  means  of  the  device  d 

is    essentially   different   from   the   foregoing.      The 


(GO 


FIG.  55. 

crucible  A  contains  the  charge,  which  consists  of 
95  parts  magnesium  chloride,  75  parts  chloride  of 
potassium,  and  6-7%  fluor-spar.  Retort  B  con- 
tains the  alumina,  which  is  reduced  by  means  of 
the  magnesium  separated  at  the  crucible  wall  (the 
crucible  being  here  again  the  cathode)  : 


The  aluminum  is  collected  on  the  bottom  of 
the  retort  B,  while  the  magnesia  in  crucible  A 
remakes  magnesium  chloride,  which  is  then  dis- 
solved anew. 


130  PRODUCTION   OF  ALUMINUM. 

Process  of  Hampes,  Kleiner. — This  rests  upon  the 
electrolysis  of  aluminum-sodium  double  fluoride 
(cryolite)  per  se,  or  mingled  with  a  salt  of  the 
alkalis  or  of  alkaline  earths.  The  bath  is  first 
melted  in  the  arc,  and  from  then  on  maintained  in 
a  molten-flow  state  by  means  of  the  current  itself. 

Omlot,  Bottiger,  and   Seidler   Process   (Fig.   56).- 
Aluminum-halogen   salts   are   melted   and    electro- 
lyzed.     A  peculiar  feature  of  this  patent,  according 


FIG.  56. 

to  which,  it  is  said,  operations  are  carried  on  in 
Crossnitz,  consists  in  the  employment  of  muffles 
6,  c  without  floors,  which  are  immersed  in  the 
melt  and  of  which  one  contains  the  positive,  the 
other  the  negative  electrode;  both  electrodes  alike 
are  deeply  immersed  in  the  bath,  which  by  means 
of  an  exterior  source  of  heat  is  kept  molten. 

The  halogens  escape  through  the  opening  /.     The 


PROCESSES.  131 

muffles  consist  of  fire-clay  with  carbon  lining,  and 
are  cemented  air-tight ;  an  indifferent  gas  provides 
for  the  exclusion  of  air. 

Roger  Process. — In  the  course  of  his  researches 
with  reference  to  the  production  of  aluminum,  Roger 
is  said  to  have  been  led  to  mix  with  the  aluminum 
salt  an  alloy  of  lead  and  sodium;  this  operation, 
according  to  the  inventors'  statement,  should 
materially  increase  the  output. 

The  lead-sodium  alloy  will  receive,  by  electroly- 
sis, a  common-salt  melt,  with  molten  lead  for  the 
cathode. 

Lossier  Process.— This  process  depends  upon  the 
electrolysis  of  aluminum  fluoride,  which  is  formed 
chemically  in  the  melt.  Lossier,  with  this  end  in 
view,  introduces  into  the  melt  a  quantity  of  cal- 
cium fluoride  and  aluminum  silicate  (Al2O3.SiO2), 
which  is  converted  at  the  prevailing  temperature 
into  aluminum  fluoride,  which  is  to  be  electrolyzed, 
and  into  calcium  silicate,  which  remains  floating 
in  the  bath: 

3CaF2  +  Al2O3.3SiO2  =  A12F6  +  3CaO.SiO2. 

The  metal  obtained  includes  considerable  quan- 
tities of  silicon.  Since  under  the  prevailing  con- 
ditions the  density  of  the  melt  is  greater  than  that 
of  the  aluminum,  the  latter  does  not  sink  beneath, 
but  rises  to  the  surface  of  the  electrolyte ;  and  a 
great  loss  of  metal  is  hereby  suffered,  since  the 


132  PRODUCTION   OF   ALUMINUM. 

metal  cannot  be  assembled  quickly  enough  to  pre- 
vent it  from  being  oxidized. 

Bucherer  Process  *  and  the  Aluminium-Industrie- 
Aktien-Gesellschaft  Process.f —  Both  patents,  which 
date  from  the  same  year  (1890),  rest  upon  the  sepa- 
ration of  aluminum  from  a  molten  solution  of  alu- 
minum sulphide  in  chlorine  alkalis.  According  to 
Bucherer,  alumina  may  be  changed  in  two  ways 
into  the  aluminum-sodium  double  sulphide:  either 
by  treating  alumina  by  heating  with  sodium  sul- 
phide, carbon,  and  sulphur: 

3Na2S  +  A1203  +  3C  +  38  =  Na6Al2S6  +  3CO, 

or  at  white  heat,  through  the  effect  of  carbon 
and  sulphur  upon  the  oxide :% 

A12O3  4-  3C  +  3$  =  3CO  +t  A12S3. 

The  sulphides  thus  obtained  are  dissolved  in  molten 
alkaline  chlorides  and  subjected  to  electrolysis.  If 
the  necessary  heat  of  reaction  is  furnished  by 
means  of  the  electrical  current  alone,  the  tension 
amounts  to  5  volts ;  if,  on  the  other  hand,  a  portion 
of  the  heat  is  added  from  outside,  from  2.3  to 
3  volts  is  sufficient. 

Pe*niakoff  Process  and  Gooch  Process. — Here,  like- 
wise, we  have  to  do  with  the  electrical  decompo- 
sition of  aluminum  sulphide.  With  regard  to  the 
Peniakoff  process  for  aluminum  production  we  pos- 

*  D.  R.  P.  No.  63995,  Nov-  l8.  l89°- 
t  D  R.  P.  No.  69909,  Nov.  18,  1890. 
J  Zeitschrift  fur  angewandte  Chemie,  1892. 


PROCESSES. 


133 


sess,  it  is  true,  only  very  scanty  data,  so  that  we  are 
obliged  to  content  ourselves  with  a  mere  reference. 
Much  better  known  and  also  of  more  recent  date 
is  the  process  of  Gooch,  which  rests  upon  the 
electrolysis  of  aluminum  sulphide,  the  latter  being 
produced  in  the  electrolytic  bath  at  the  expense 
of  the  alumina  dissolved  therein.  The  inventor 


FIG.  57. 

mixes  a  composition  of  sodium  fluoride  and  alu- 
minum chloride.  He  completes  the  melt  with  the 
addition  of  alumina,  and  conducts  a  current  of 
bisulphide  of  carbon  through  it.  This,  according 
to  Gooch,  is  produced  in  the  electrolytes  directly 
before  the  introduction,  by  conducting  sulphur- 
vapors  over  a  thick  layer  of  carbon  brought  to  a 
red  glow;  the  precaution  must  be  taken,  however, 


134  PRODUCTION  OF  ALUMINUM. 

to  generate  the  bisulphide  of  carbon  beforehand, 
independently  of  the  electrolysis.  Furthermore, 
Gooch  believes  that  the  bisulphide  of  carbon  may 
be  replaced  by  any  other  sulphur  compound — for 
example,  by  sulphuretted  hydrogen. 

The  alumina  dissolved  in  the  bath  is  changed  by 
the  gas  into  the  sulphide,  and  the  latter  is  imme- 
diately decomposed  by  the  electric  current,  with  the 
separation  of  aluminum. 

The  apparatus  described  by  the  inventor  in  his 
English  patent  (No.  16555  of  August  15,  1899) 
is  depicted  in  Fig.  57. 

T  is  an  iron  crucible,  whose  bottom  and  walls 
are  lined  to  the  height  of  the  anodes  with  a  layer 
of  carbon.  The  walls  above  the  anodes  and  the 
tubes  55',  in  which  the  anodes  CCr  slide,  are  lined 
with  alumina,  so  that  the  anodes  are  introduced 
insulated  into  the  crucible.  The  anodes  are  con- 
nected with  the  positive  pole  of  the  dynamo  by 
means  of  the  pins  rr',  the  bar  K,  and  the  cable  P. 
Clamp  mf  and  cable  N  are  the  means  of  uniting  the 
crucible  to  the  negative  pole  of  the  machine. 

The  anodes  are  hollow  and  provided  with  tube 
feeders  GG't  which  serve  for  the  introduction 
of  bisulphide  of  carbon.  The  cap  /,  above  the 
crucible,  consists  of  iron,  lined  with  carbon.  R  is 
a  drawing-off  tube.  This  chimney-like  headpiece 
/  is  supported  by  the  beam  7',  which  may  be 
fastened  upon  the  bar  K  by  means  of  the  pressure- 
screw  y.  During  the  electrolysis  the  cap  is  dipped 


PROCESSES.  135 

slightly  into  the  melt,  whose  upper  surface,  remain- 
ing free,  is  covered  with  a  carbon  layer  p. 

When  the  apparatus  is  to  be  operated,  first  of  all 
a  composition  of  aluminum  chloride  and  sodium 
fluoride  is  melted  down  in  the  crucible,  then  alu- 
mina is  added  and  bisulphide  of  carbon  introduced. 
The  effect  of  the  latter,  as  we  have  already  remarked 
above,  is  to  make  aluminum  sulphide  from  alumina ; 
the  aluminum  sulphide  is  dissolved  in  the  melt, 
also  carbonic  oxide  and  carbonic  oxysulphide,  which 
escape  through  the  dra wing-off  tube  R. 

The  sulphide  is  decomposed  by  the  electric  cur- 
rent; at  the  walls  of  the  crucible  aluminum  is 
separated,  which  is  assembled  at  the  bottom  of  the 
crucible,  while  sulphur  escapes.  The  regeneration 
of  the  bisulphide  of  carbon  follows,  according  to  a 
peculiar  process  described  in  the  patent. 

The  inventor  asserts,  furthermore,  that  he  has 
obtained  very  good  results  with  the  electrolysis  of 
a  compound  of  aluminum  fluoride  and  alkali  fluoride, 
with  the  addition  of  alumina  and  the  introduction 
of  bisulphide  of  carbon. — The  Gooch  process  does 
not  appear  as  yet  to  have  been  technically  utilized. 


PART  II. 

ALUMINUM  AND  ITS  ALLOYS.     METHODS 
OF  WORKING  AND  USES. 

A.  THE  ALUMINUM  INDUSTRY. 

Since  the  year  1889 — despite  numerous  asser- 
tions to  the  contrary — there  has  been  a  very  remark- 
able increase  in  the  use  of  aluminum  in  commerce 
and  in  industry;  the  metal  is  at  present  utilized  in 
all  forms  and  dimensions,  from  thimbles,  visiting- 
cards,  etc.,  which  weigh  but  a  fraction  of  a  gram, 
to  objects  of  several  tons'  weight,  such  as  ship- 
propellers  and  the  like. 

Among  the  metals  with  which  aluminum  is  alloyed 
the  most  important  are  iron,  copper,  nickel,  and 
German  silver.  The  forms  in  which  the  metal  is 
utilized,  either  by  itself  or  in  alloy,  are  exceedingly 
numerous;  in  commerce  we  recognize  bar-,  wire-, 
plate-,  tube-,  and  powdered  aluminum. 

The  percentage  of  iron  should  not  exceed  2%; 
from  3  to  6%  of  other  metals  may  be  present.  The 
alloys  possess  a  tensile  strength  of  25-35  kg  per 
mm2,  with  an  elongation  of  5-10%;  the  pure 

metal,  on  the  other  hand,  annealed,  shows  a  tensile 

136 


'    THE  ALUMINUM  INDUSTRY.  137 

strength  of  only  15-20  kg  per  mm2,  with  an  exten- 
sion of  3°-5°%' 

Aluminum  may  also  be  used  for  heavy  alloys. 
Copper  or  brass  alloyed  with  3-10%  of  aluminum 
gives  bronzes  capable  of  a  high  resistance. 

Aluminum  has  been  the  subject  of  a  large  number 
of  researches,  which  have  had  reference  in  part  to 
its  chemical  constitution  (pure  metal  or  alloy),  in 
part  to  the  method  of  working  the  metal,  its  resist- 
ance to  chemical  influences  (sea-water,  atmos- 
phere), its  analysis,  and  its  metallurgical  and  chem- 
ical utilization  as  a  reducing-agent. 

Production  of  Aluminum.  —  It  is  doubtless  to  the 
electrolytic  methods  that  aluminum  owes  its  increas- 
ing production  and  consumption  of  late  years.  The 
world's  production  of  aluminum,  which  even  in  the 
year  1889 — hence  at  a  time  when  the  electrolytic 
production  of  aluminum  was  just  beginning  its 
rapid  development — did  not  amount  to  more  than  70 
tons,  increased  in  the  year  1900  to  5000-6000  tons. 

The  buying-price  of  aluminum,  during  the  same 
period,  fell  from  30  to  3  fr.  per  kilogram  of  the 
metal.  In  the  year  1855,  at  the  time  of  Deville's 
researches,  the  kilogram  of  aluminum  cost  1000  fr. ;' 
in  the  succeeding  year  the  price  fell  to  375  fr. 
per  kilogram. 

Morin  in  Nanterre  (1857)  lowered  the  price  to 
280  fr. ;  from  1857  to  1886  Merle  &  Co.  and  later 
Pechiney,  in  Salindres,  kept  it  at  about  125  fr. 
From  1886  to  1892  England  operated  with  the 


'38 


PRODUCTION  OF  ALUMINUM. 


chemical  processes  of  Netto  and  Castner,  which 
represent  the  perfection  of  Deville's  method,  but 
which  were  not  able  to  furnish  aluminum  at  a 
price  lower  than  20  fr.  per  kilogram.  Carefully 
planned  as  these  processes  were,  they  finally  had 
to  give  way  to  the  electrolytic  methods,  whicfy 
lowered  the  price  of  aluminum  to  3  fr.,  and 
thus  converted  the  metal  into  one  industrially 
available. 

Table  IX  shows  the  increase  in  the  production 
of  aluminum  in  the  various  countries,  from  1885 
down  to  our  own  day.  (See  Appendix,  page  218.) 


TABLE  IX. 

PRODUCTION   OF   ALUMINUM. 
(In  tonnes  =  1000  kg.) 


Year. 

U.S.A. 

Switzerland 

France. 

England. 

Germany. 

1885 

i 

2 

I 

10 

1886 

2 

.... 

3 

I 

10 

1887 

8 

.... 

2 

I 

15 

1888 

8 

.... 

4 

II 

15 

1889 

22 

.... 

15 

34 

15 

1890 

28 

41 

37 

70 

1891 

76 

169 

36 

52 

1892 

134 

237 

75 

4i 

J893 

141 

437 

!37 

1894 

37° 

600 

270 

1895 

4i7 

650 

360 

1896 

59° 

700 

500 

1897 

1184 

800 

500 

300 

1898 

1300 

960 

600 

360 

1899 

1500 

I  I2O 

700 

420 

300 

1900 

1650 

1232 

800 

500 

500 

Total  production 

743i 

6946 

4041 

1791 

850 

THE  ALUMINUM  INDUSTRY.  139 

In  respect  to  the  amount  of  aluminum  produced, 
the  United  States  is  in  the  first  rank;  then  follow 
Switzerland,  France,  England,  and  Germany. 
Thanks  to  the  new  establishment  in  Rheinfelden, 
which  was  erected  by  the  Aluminium-Industrie- 
Aktien-Gesellschaft,  the  production  of  Germany  will 
soon  be  equal  to  that  of  France  and  Switzerland; 
indeed,  this  may  already  be  the  case  to-day. 

Of  all  countries  producing  aluminum,  France 
has  decidedly  the  most  favorable  local  conditions, 
for  it  is  a  country  possessing  not  merely  natural 
sources  of  power,  which  permit  of  the  easy  and 
successful  enlargement  of  the  new  industry,  but 
also — in  contrast  to  other  countries — extensive 
deposits  of  bauxite,  which  furnishes  the  neces- 
sary originative  material  for  the  production  of 
aluminum. 

According  to  Table  IX,  the  total  production  of 
aluminum  from  1885  to  and  including  1900  amounts 
to  21060  tonnes.  The  5000  tonnes  which  were  pro- 
duced in  the  year  1900  represent  a  purchase-price 
of  13 \  million ,  francs,  and  demand  an  electrical 
power  of  25000  h.p.,  employed  uninterruptedly 
night  and  day.  The  available  energy  which  would 
be  at  the  disposal  of  all  the  establishments  which 
produce  aluminum,  when  worked  to  the  extent 
of  their  capacity,  is  far  greater;  it  amounts  to 
61000  h.p. 

The  capital  invested  in  the  aluminum  industry  is 
very  considerable.  The  capital  of  the  Compagnie 


140 


PRODUCTION  OF  ALUMINUM. 


Establishment. 

Place. 

Process. 

Avail- 
able 
Energy, 
H.P. 

Compagnies   des    pro- 

France: 

du  i  t  s        chimiques 

d'Alais  et  de  la  Ca- 

Minet- 

margue 

St.  Michel  (Savoy) 

Hall 

6000 

La    Praz    (Savoy) 

Societe     e'lectrome'tal- 
lurgique  francaise 

Froges       (Isdre) 
Gardannes 
(B  ouches     du 

HeVoult 

6000 

Rhone)           •; 

Switzerland: 

Neuhausen 

He"roult 

6000 

Aluminium  -  Industrie- 

Germany: 

Aktien-Gesellschaft 

Reinfelden 

H6roult 

5000 

Austria: 

Land-Gastein 

•He"roult 

4000 

Pittsburg     Reduction 

United  States: 

Company 

Niagara    Falls 

Hall 

2OOOO 

England: 

British  Aluminium 

Foyers    (Scotland) 

H6roult 

I4OOO 

des  produits  chimiques  d'Alais  et  de  la  Camargue, 
invested  in  the  factory  at  St.  Michel,  amounts  to 
2.2  million  fr.,  that  of  the  Pittsburg  Reduction 
Company  to  15  million  fr. ;  the  Societe  electro- 
metallurgique  franchise  has  a  capital  of  10  million 
fr. ;  the  aluminum  establishments  of  Switzerland 
represent  a  property  of  18  millions,  the  British 
aluminium  15  millions,  the  Aluminum-Industrie- 
Aktien-Gesellschaft  19  millions;  the  total  capital 
invested,  therefore,  amounts  in  round  numbers  to 
79  million  francs. 

The  majority  of  these  companies  unite  with  the 
industrial  production  of  aluminum  still  other 
branches  of  production:  the  electrometallurgical 


THE  ALUMINUM  INDUSTRY.  141 

production  of  sodium  and  magnesium,  the  pro- 
duction of  ferro-silicon,  ferro-chrome,  ferro-man- 
ganese,  of  metallic  carbides  and  metallic  silicides, 
etc. 

Cost  of  Producing  Aluminum. — An  exact  state- 
ment as  to  the  cost  of  a  kilogram  of  aluminum  is, 
in  view  of  the  large  number  of  elements  entering 
into  the  question,  hardly  possible;  the  cost  is, 
of  course,  influenced  by  the  greatest  variety  of 
circumstances:  by  the  electromotive  force,  the 
rate  of  compensation  for  labor,  the  electrode 
material,  the  originative  material  (alumina  and 
natural  or  artificial  cryolite),  the  labor  of  refining, 
etc.  Nevertheless  we  give  below  some  figures 
which  obtain  for  an  establishment  of  1000  horse- 
power, working  with  water-power  (average  head 
100-150  m). 

Electric  Energy. — In  general  it  may  be  said  that 
the  production  of  a  kilogram  of  aluminum  requires 
in  round  numbers  40  electric  horse-power  hours. 
Under  the  specified  conditions  (water-power)  the 
effective  horse-power  hour,  measured  at  the  elec- 
trolytic apparatus,  costs  i  centime,  including  gen- 
eral oversight,  surveillance  of  the  flow  of  water,  of 
the  turbines  and  the  electrical  machines.  The 
kilogram  of  aluminum,  then,  in  so  far  as  the  elec- 
trical energy  is  concerned,  comes  to  0.40  fr. 

Electrodes. — With  apparatus  in  which  the  crucible 
serves  simultaneously  as  cathode,  the  costs  of  the 
cathode  material  may  be  reckoned  at  200  fr.  for 


142  PRODUCTION  OF  ALUMINUM. 

800  kg  aluminum,  which  makes  0.2 5  fr.  per  kilogram 
of  aluminum  produced.  On  the  other  hand  the 
waste  of  the  anodes  amounts  to  about  1200  g  per 
kilogram  of  the  metal ;  since  the  kilogram  of  carbon 
anode  may  be  taken  at  0.20  fr.,  we  have  to  allow 
for  every  kilogram  of  aluminum  an  anode  waste 
of  0.24  fr. ;  taken  altogether,  then,  a  kilogram 
of  aluminum  costs  0.49  fr.  in  electrode  material. 

Payment  for  Labor. — For  the  supervision  of  a 
group  of  apparatus  which  produces  50  kg  aluminum 
one  laborer  suffices  for  day  and  night  service.  This 
represents  an  expenditure  of  10  fr.  per  50  kg, 
hence  0.20  fr.  per  kilogram  of  the  metal. 

Originative  Materials. — Under  this  classification 
belongs  the  charging  of  the  bath  at  the  beginning 
of  the  electrolytic  process  with,  on  the  average, 
50%  of  cryolite  and  50%  of  chlorides  and  fluorides 
of  the  alkalis  and  alkaline  earths;  also  the  main- 
tenance of  the  process,  and  the  completion  of  the 
melt  with  anhydrous  alumina  during  the  course 
of  the  electrolysis.  As  for  the  original  charge  of 
the  bath,  we  must  calculate  the  requisites  for  this 
as  costing  on  the  average  0.30  fr.  per  kilogram 
of  aluminum.  The  continued  filling  up  demands 
2.2  kg  of  anhydrous,  chemically  pure  alumina,  the 
kilogram  costing  0.50  fr. ;  consequently  the  cost  is 
1. 10  fr.  per  kilogram  of  the  metal;  the  total  cost 
is,  therefore,  1.40  fr.  To  this  should  be  added  the 
expenditure  for  the  remelting,  which  amounts 
to  about  o.io  fr. ;  so  that  we  may  reckon  the  costs 


THE  ALUMINUM  INDUSTRY.  143 

of  material  for  a  kilogram  of  metal  at  a  total  of 
1.50  fr. 

Maintenance  of  ike  'Establishment;  Unforeseen 
Expenditures. — In  the  price  of  i  centime  for  the 
electric  horse-power  hour  we  have  included  merely 
the  paying  off  of  the  capitalization.  For  the 
maintenance  of  the  establishment  (melting-fur- 
naces, workshops,  chemical  products,  etc.)  we  may 
name  the  sum  of  15000  fr.  for  a  yearly  production 
of  150  tons  of  aluminum;  that  is  to  say,  o.io  fr. 
per  kilogram  of  metal ;  the  unforeseen  expenditures 
may  be  reckoned  at  about  the  same  amount. 

To  recapitulate  what  we  have  said,  the  cost  of 
manufacture  may  be  stated  as  follows: 

Cost  of  Manufacture  for  a  Kilogram  of  Aluminum. 

Francs. 

Electrical  energy :   40  electric  horse-power  hours o .  40 

L  Cathode:  200  fr.  for  800  kg  aluminum  =  o . 2 5  fr. 
Electrodes  •<  Anode:    1200  g@o.2o  fr.  per   kg   of   anode- 

(  weight  =0.24  fr 0.49 

Cost  of  labor:   two  laborers  @  10  fr.  for  50  kg  aluminum. .   o  .  20 
(  Charge  and  completion  of  the  bath,    o  .  30  fr. 

Materials:    <  Alumina  22.  kg  @  0.50  fr i .  10  fr. 

'  Remelting  (coke  and  crucibles). .  .  .    o.io  fr.   i  .50 
Maintenance  and  unforeseen  expenses 0.20 


Total.  . 2  .  79 

We  thus  obtain  a  price  in  the  neighborhood  of  3 
fr.,  which,  in  fact,  is  the  actual  purchase-price.  To 
be  sure,  most  establishments  avail  themselves  of  a 
greater  power  than  we  have  assumed  in  the  above 
reckoning,  so  that  they  can  obtain  the  horse-power 


144  PRODUCTION  OF  ALUMINUM. 

hour  more  cheaply;  furthermore,  we  must  not 
overlook  various  improvements  which  have  been 
made,  as  for  example  in  the  production  of  the 
electrodes  and  of  the  originative  materials,  espe- 
cially alumina.  Further  investigations  will  un- 
doubtedly lead  to  yet  further  improvements;  how- 
ever, it  may  certainly  be  said  that  the  electro- 
metallurgy of  aluminum  has  already  attained  a 
degree  of  perfection  beyond  which  we  can  scarcely 
make  any  material  advance. 

B.  ALUMINUM  AND  ITS  ALLOYS. 

Aluminum  is  employed  not  merely  in  the  pure 
condition,  but  also  as  an  alloy,  namely,  as  a  con- 
stituent of  light,  heavy,  and  medium-weight  alloys. 

(a)  Pure  Aluminum. 

Pure  aluminum  is  used  where  the  requirement  is 
not  extraordinary  mechanical  stability,  but  strong 
resistance  to  chemical  influences. 

The  atomic  weight  of  aluminum  is  27.08.  Its 
density  varies,  according  to  the  treatment  to 
which  it  is  subjected,  between  2.6  and  2.74.  It 
melts  at  650°  C.  and  has  a  white  color  and,  especially 
on  freshly  cut  surfaces,  a  beautiful  lustre.  In  the 
air  it  does  not  change  appreciably  if  it  is  free  from 
"silicon.  If  it  contains  this  element  to  a  consider- 
able extent  (0.5-1%),  an  exchange  would  appear 
to  take  place  in  the  interior  of  the  metal;  the 
silicon  goes  to  the  surface,  is  oxidized,  and  forms  a 


ALUMINUM  AND   ITS  ALLOYS.  145 

thin  layer  of  silica,  which  may  be  wiped  off  at 
a  touch. 

Aluminum  is  able  to  reduce  almost  all  oxides, 
even  those  of  carbon,  silicon,  and  boron.  Water 
and  dilute  organic  acids  scarcely  affect  aluminum 
at  all;  at  a  boiling  heat,  it  is  true,  it  is  attacked 
by  organic  salts,  but  only  very  gradually.  Nitric 
acid  is  almost  entirely  ineffectual ;  by  sulphuric  acid 
aluminum  is  dissolved  gradually,  by  hydrochloric 
acid  and  by  alkalies  rapidly  and  easily.  Below,  in 
the  part  which  treats  of  the  working  of  aluminum, 
we  shall  adduce  some  further  researches,  which 
have  to  do  with  its  resistance  to  chemical  reagents. 

Mechanical  Properties  and  Electrical  Conductivity. — 
Charpentier-Page  of  Valdoie  (Belfort  District) 
has  instituted  some  very  interesting  experiments 
with  regard  to  the  mechanical  properties  of  pure 
aluminum  and  of  its  alloys,  as  well  as  their  electrical 
conductivity.  We  give  below  some  of  his  results; 
in  the  first  place,  those  that  have  to  do  with  pure 
aluminum  in  the  form  of  wire. 

TABLE  X. 
Pure  Aluminum. 

ANNEALED    WIRE. 

2  mm.  diam.     Density  2.688. 
Electrical  Tests. 

Resistance  per  metre o .  00919/1 

Resistance  of  a  wire  of  i  mm2  cross-section  per  km .    28  . 86D, 
Resistance  of  a  copper  wire  of  the  same  dimensions, 

at  22°  C 17.9/2 

Proportion  of  conductivities 62% 


146 


PRODUCTION  OF  ALUMINUM. 

Mechanical  Tests. 


Test. 

I 

a 

3 

Length  of  the  test-piece  mm 
Elongation                                      ' 

no 
*6 

no 

•2  f 

110 

•JA       C 

Elasticity                                       kg 

•22     7O 

•27       2 

O'*  •  O 
7  2      2 

per  mm2            .  .          ' 

IO     tl 

IO    ^7 

I  O      ^7 

Elongation  % 

•22     7 

ii   8 

21       7 

HARD    WIRE. 

2  mm  diam.     Density  2.694 
Electrical  Tests. 

Resistance  per  metre o . 00928^ 

Resistance  of  a  wire  of  i  mm2  cross-section  per  km .    29.15/2 
Resistance  of  a  copper  wire  of  the  same  dimensions, 

at  22°  C 17.9/2 

Proportion  of  conductivities 61% 

Mechanical  Tests. 


Test. 


i 

2 

3 

Length  of  the  test-piece.  .  .  . 

.mm 

no 
4  •  ^ 

no 

4  .  ^ 

IIO 

4 

.  kg 

72 

72  .  7 

72.1; 

per  mm2 

,? 

22     O 

27     14 

27    O  < 

Elongation                           .  .  . 

.  % 

4 

4" 

l   6 

From  this  tabulation  may  be  seen  the '  advan- 
tage aluminum  offers  as  conducting  material.  If 
one  compares  the  above  figures  for  aluminum 
with  those  for  copper,  one  sees  that  at  current 
prices  for  both  sorts  of  wire  aluminum  wire  with 
the  like  conductivity  is  cheaper  than  copper  wire. 
If  100  is  the  conductivity  for  copper,  62  is  that 


ALUMINUM  AND   ITS  ALLOYS.  147 

for  aluminum.  8.95  is  the  density  of  copper, 
2.67  the  density  of  aluminum ;  a  kilogram  of  copper 
wire  costs  2.75  fr.,  a  kilogram  of  aluminum  wire 
3.75  fr.  With  a  like  conductivity,  the  cross-section 

100 
of  the  aluminum  wire  Sc  =  -^~  =1.61,  that  of  the 

copper  wire  Sc  being  placed  equal  to  i.  Under 
the  same  conditions  the  weight  of  the  aluminum 
wire  Qa  =  1.61  X2.67  =4.3,  that  of  the  copper  wire 
Qc  =  i  X8.95  =8.95.  The  price,  therefore,  for  alu- 
minum wire  stands  at  Pa  =  4. 3X3. 75  =  16.13  fr-  \ 
for  copper  wire,  on  the  other  hand,  at  Pc  =  8. 95X2. 75 
=  24.6  fr. 

Uses. — Aluminum  in  the  pure  state  serves  for 
the  manufacture  of  electrical  conductors,  for  surgi- 
cal apparatus,  precision-instruments,  artistic  objects, 
cooking  utensils;  also  in  chemistry  as  a  reducing- 
agent  in  the  production  of  certain  metals,  such  as 
chrome,  manganese,  vanadium,  uranium,  etc. 

(6)  Heavy  Alloys. 

Among  the  heavy  alloys  aie  reckoned  the  various 
kinds  of  aluminum  bronze  and  brass,  and  also  some 
alloys  in  which  zinc  predominates,  such  as  those  of 
Cothias.  The  first-named  aluminum  alloys  have 
already  been  utilized  industrially  for  a  long  time, 
because  of  their  notable  mechanical  properties. 
They  take  a  high  polish  and  withstand  atmos- 
pheric influences  excellently. 


148  PRODUCTION  OF  ALUMINUM. 

Aluminum  Bronze.  —  Alloys  with  7.5%  of  alu- 
minum and  92.5%  of  copper  have  a  golden  color, 
but  are  less  durable  than  similar  alloys  containing 
10%  of  aluminum.  In  practice  this  proportion  is 
seldom  exceeded,  since  an  alloy  containing  a  higher 
percentage  of  aluminum  is  very  brittle. 

Aluminum  bronzes  are  used,  in  a  small  way,  for 
the  manufacture  of  optical  instruments,  table- 
ware, ornaments,  etc. ;  on  a  larger  scale,  for  ship- 
propellers,  armor-plate,  etc. 

Bronzes  containing  2.5,  5,  and  10%  correspond 
to  the  formulae:  Cu2Al  (with  9.62%  Al),  Cu8Al 
(with  5-05%  Al),  Cu16Al  (with  2.59%  Al). 

Aluminum  Brass.  —  The  amounts  of  aluminum 
and  zinc  vary.  Usually  the  composition  is  as 
follows : 


Copper 67        71          55.8      55.8      67.7     percent 

Zinc 3°         27.5      42  43  26.8 

Aluminum.  . 3  1.5        4.2         1.2        5.8 


The  tensile  strength  of  the  first  two  alloys  varies 
from  21-45  kg  per  mm2;  that  of  the  next  two 
amounts  to  50  kg;  in  the  case  of  the  fifth  alloy  a 
tensile  strength  up  to  65  kg  would  be  obtained.  A 
proposal  in  The  Aluminum  World  is  worth  noting, 
according  to  which  zinc  and  aluminum  are  to  be 
added  to  the  copper,  in  the  form  of  a  previously 
prepared  zinc-aluminum  alloy  containing  from  5  to 
10%  of  the  last-named  metal.  There  is  a  larger 
percentage  of  aluminum  in  the  zinc-aluminum 


ALUMINUM  AND  ITS  ALLOYS.  149 

alloys  of  Cothias — alloys  which  are  easily  poured 
and  may  advantageously  replace  cast  zinc. 

Researches  Concerning  Aluminum  Bronze  and 
Brass. — These  alloys  have  been  the  subject  of 
countless  investigations,  among  which  should  be 
mentioned  the  researches  of  Debray,  who  first 
prepared  bronzes  with  10%  of  aluminum,  then  the 
investigations  of  Cowles  and  Heroult,  who  for 
the  first  time  produced  aluminum  bronzes  for  tech- 
nical purposes.  Among  the  results  of  Heroult 
which  relate  to  the  bronzes  obtained  in  Froges 
and  in  Schaffhausen,  it  is  worthy  of  special  note 
that  a  bronze  with  10.5%  of  aluminum,  before  it 
has  had  any  mechanical  working,  and  hence  in 
the  rough  state  in  which  it  has  come  from  the 
melt,  has  an  elasticity  of  63.8  kg  per  mm2,  with 
an  elongation  of,  6.8%.  With  a  special  alloy — 89 
parts  copper,  10  parts  aluminum,  i  part  silicon — 
Cowles  obtained  a  strength  of  100.5  kg.  Pouthiere, 
professor  in  the  University  of  Lou  vain,  found  in 
his  tests  in  the  establishment  at  Malines  with  cast 
bars  8  mm  in  diameter,  which  came  from  the 
Cowles  works  in  Lockport,  a  strength  of  69.31  kg, 
with  a  simultaneous  elongation  of  4.3%;  the  alloy 
in  question  contained  90.15%  Cu,  8.10%  Al,  and 
i-75%  Si. 

A  noteworthy  investigation  of  aluminum  bronzes 
and  similar  alloys  we  owe  to  Andre  Le  Chatelier, 
who  made  researches  into  the  molecular  changes 
that  occur  when  rolled  and  drawn  aluminum  bronzes 


PRODUCTION  OF  ALUMINUM. 


are  heated,  and  compared  his  results  with  analo- 
gous conditions  in  the  case  of  copper. 

The  following  table  gives  the  results  obtained  by 
Le  Chatelier,  on  the  one  hand  with  steam-tubes 
of  10%  aluminum  bronze,  and  on  the  other  hand 
with  copper  tubing. 

TABLE  XI. 

ELASTICITY    OF     COPPER     AND     OF     IO%     ALUMINUM     BRONZE,    IN 
RELATION    TO    TEMPERATURE. 


Copper. 

10%  Aluminum  Bronze. 

Temperature, 

t°C. 

Elasticity. 

Elongation. 

Elasticity. 

Elongation. 

IS 

25.2 

30% 

S3-2 

19% 

JOO 

22.9 

30% 

52-4 

22% 

15° 

2O 

30% 

51 

21% 

2OO 

16  .9 

30% 

49.2 

22% 

250 

14 

29% 

47 

21% 

300 

12.7 

20% 

44-2 

19% 

350 

9-4 

15% 

37 

15% 

40O 

7 

10% 

23.2 

21% 

460 

3-6 

10 

23% 

These  figures,  which  need  no  further  explanation, 
clearly  indicate  the  superiority  of  aluminum  bronze. 
Thus  we  find,  for  example,  that  at  350°  C.  the 
strength  of  copper  has  been  diminished  by  60%, 
while  that  of  the  bronze  is  lessened  only  by  40%; 
and  that  the  strength  of  the  bronze  at  350°  C.  is 
practically  the  same  as  that  of  the  copper  at  1 5°  C. 

When  Le  Chatelier  came  further  to  compare  the 
effect  of  heat  on  10  and  9%  cast  bronze,  he  found 
that  with  an  increase  in  temperature  from  15°  C. 


ALUMINUM  AND  ITS  ALLOYS.  151 

to  400°  C.  the  tenacity  of  the  first  alloy  is  diminished 
by  30%,  that  of  the  second,  on  the  other  hand, 
by  70%.  Cast  bronzes  with  9  and  5%  of  aluminum 
show  in  the  temperature-interval  from  15-380°  C. 
a  like  relation;  in  the  case  of  both  alloys  the  te- 
nactiy  is  diminished  by  30%. 

If,  in  making  bronze,  the  aluminum  is  added 
molten  to  the  copper,  a  rise  in  temperature  is 
observed;  this  development  of  heat  is  regarded  by 
some  investigators  as  proof  of  a  chemical  union 
of  the  two  metals.  Kiliani  is  nevertheless  of  the 
opinion  that  this  increase  of  temperature  is  not 
conclusively  and  necessarily  to  be  ascribed  to  such 
union,  but  in  large  part  also  to  the  reaction  between 
aluminum  and  copper  protoxide,  which  latter  is 
always  contained  in  commercial  copper.  He  ad- 
vances the  following  reason  for  this  hypothesis: 
If  one  part  of  aluminum  be  added  to  nine  parts 
of  copper, — not  all  at  once,  however,  but  a  little 
at  a  time, — there  is  presently  a  significant  increase 
of  temperature,  while  the  last  portions  of  aluminum, 
owing  to  the  latent  heat  of  fusion,  effect  a  lower- 
ing of  the  temperature. 

Aluminum  bronzes  strongly  resist  salt  solutions 
and  sulphurous  liquids.  In  the  laboratory  of  the 
works  at  Neuhausen  plates  of  various  alloys  were 
exposed  for  fourteen  days  to  the  action  of  solutions 
which  contained  3%  of  cooking-salt  and  4%  of 
acetic  acid.  The  relative  losses  in  weight  were  as 
given  below: 


152  PRODUCTION  OF  ALUMINUM. 

Loss  in  Weight. 

Bronze  with  10%  aluminum,  free  from  silicon i      part 

"  "        "  "  with  2.8%  Si 2.1  parts 

Brass  3-5%  aluminum 4.4     " 

Phosphor-bronze 32          " 

The  same  alloys,  on  being  exposed  to  sea-water, 
showed  losses  in  weight  as  follows: 

Loss  in  Weight. 

Bronze  with  10%  aluminum,  free  from  silicon i  part 

with  2.8%  Si 39  parts 

Brass  with  3.5%  aluminum 101     " 

Phosphor-bronze 1 16     " 

In  the  Journal  of  the  Society  of  Chemical  Industry 
are  assembled  a  great  number  of  results,  based  upon 
manifold  tests,  which  concern  themselves  with  vari- 
ous sorts  of  steel,  with  pig  iron,  cast  iron,  cannon 
bronze  and  aluminum  bronze.  The  most  important 
data  are  reproduced  herewith: 

TABLE  XII. 

Steel,  Pig  Iron,  Cast  Iron. 

Elasticity 

per  mm2 

Cross-section. 

Cannon-steel,  hardened,  annealed  and  rolled 69  .  70  kg 

Steel,  neither  hardened  nor  annealed 63  . 80  " 

"   .cast 51.30  " 

Puddled  iron,  melted;  in  thin  bars 52  . 90  " 

medium  thick 38 .40  " 

Forged  iron 34-9°  " 

Cast  iron 21.70  " 

Firminy  steel  for  the  French  artillery 71 . 20  " 

Cannon  Bronze. 

Copper  88,       Tin  10,       Zinc  2  parts 28 . 30  kg 

92,  8,  2       " 21 .10    " 

9L7.     "      8.3,      "     2       " 22.50    " 


ALUMINUM  AND  ITS  ALLOYS.  153 

Aluminum  Bronze. 

Copper  89,       Aluminum  10,       Silicon  i  part 76.10  kg 

"91.50  7.5         "         o. 75  parts.  .    50.60 

The  same,  cast 47  . 10 

"       "    ,  rolled 60 . 20 

Copper  95,       Aluminum  5      parts,  rolled 60 . 10 

"      92.5  "  7-5      "         "      44 

"9i  "  9          "         "      55-90 

"90  10  69.80 

Waldo,  dissenting  from  Kiliani's  conclusion,  be- 
lieves that  he  has  demonstrated  that  aluminum 
bronze  is  not  a  simple  alloy  of  copper  and  aluminum, 
such  as,  perhaps,  the  alloy  of  copper  and  tin  (with 
the  exception  of  the  compound  SnCu3),  but  a  per- 
fectly definite  chemical  compound.  Waldo  ad- 
vances several  reasons  in  support  of  this  hypothesis, 
among  others  the  considerable  quantity  of  heat 
which  is  freed  when  one  mixes  the  two  metals, 
aluminum  and  copper,  in  a  molten  state;  Kiliani's 
objection  to  this  argument  we  have  discussed  above. 

Likewise  from  the  dependency  of  the  electrical 
conductivity  of  copper  upon  the  amount  of  alu- 
minum contained  therein,  Waldo  concludes  that  we 
have  here  a  chemical  compound,  and  no  ordinary 
alloy.  One  actually  sees,  from  the  respective  curves 
of  conductivity,  that  the  electrical  behavior  of  the 
alloy  is  dependent  in  an  unusual  degree  upon  the 
proportion  of  aluminum;  the  curve  shows  that  the 
addition  of  even  the  minutest  quantity  of  aluminum 
exerts  an  influence  disproportionately  great  upon 
the  conductivity, — a  circumstance  which  goes  to 
support  Waldo's  contention.  Furthermore,  Waldo 


154 


PRODUCTION  OF  ALUMINUM. 


refers  to  the  fact  that  we  are  unable  to  discover  any 
simple  method  of  separating  aluminum  from  cop- 
per when  we  have  both  metals  combined. 

If  one  takes  a  large  piece  of  10%  aluminum 
bronze,  it  is  possible  to  discern  neither  the  trace 
of  any  natural  joint  between  the  two  metals,  nor 
yet  the  presence  of  grains  of  aluminum  in  the  mass 
of  copper,  nor  any  other  differences  of  constitution 
in  the  alloy. 

Tests  quite  analogous  to  those  instituted  by 
Charpentier-Page  for  pure  aluminum  have  been 
carried  out  by  the  same  observer  on  10%  aluminum 
bronze. 

TABLE  XIII. 
Aluminum  Bronze. 

Aluminum  10,  Copper  90  parts. 
Hard  Wire,  1.6  mm  in  diam.     Thickness  8.2. 

Electrical  Tests. 

Resistance  per  metre o .  66&Q 

Resistance  of  a  wire  of  i  mm2  cross-section  per  km.  .  133  .  6o/i 

Test  temperature 18°  C. 

Resistance  of  a  copper  wire  under  conditions  other- 
wise similar 1 7  •  5-^ 

Proportion  of  conductivities 1 

Mechanical  Tests. 


I. 

II. 

Length  of  test-piece  in  metres  

o   10 

O     IO 

Length  at  the  load-limit  reached.  . 

o   i  30 

0128 

Elasticity 

kg 

I  20 

128 

Elasticity  per  mm2  cross-section 

•  •    *-S 

ker 

64.     ^ 

61 

Elongation  

mm 

30 

28 

ALUMINUM  AND  ITS  ALLOYS.  1 55 

We  see  from  these  figures  that  a  practical  appli- 
cation of  aluminum  bronze  for  conducting  material 
is  not  to  be  considered. 

(c)  Alloys  of  Medium  Density. 

In  this  group  belong  only  a  few  alloys  which  are 
used  industrially  as  metals,  many,  however,  which 
serve  for  solder;  we  shall  reserve  the  detailed 
description  of  the  latter  for  the  section  which  treats 
of  the  "Working  of  Aluminum."  Here  we  shall 
mention  only  colored  alloys  with  gold,  palladium, 
cobalt,  and  nickel;  also  a  special  iron-silicon-alu- 
minum, which  is  of  importance  in  metallurgy. 

Aluminum-gold  Alloy. — This  was  produced  for 
the  first  time  by  the  English  chemist  Roberts- 
Austen;  it  contains  22  parts  aluminum  and  78  parts 
gold,  and  is  of  a  purple  color,  with  a  ruby  lustre. 

This  alloy  appeared  for  a  while  destined  to  play 
a  role  for  ornamental  purposes,  and  as  a  coin- 
metal;  but  after  the  researches  of  Margot  it  was 
impossible  to  deny  that  the  metal  was  practically 
useless,  since  it  possesses  neither  the  ductility  nor 
the  malleability  to  make  it  possible  to  work  or  stamp 
the  metal  for  such  purposes. 

The  brothers  Tissier  found  that  aluminum  could 
be  alloyed  with  gold  up  to  10%  without  losing  its 
malleability.  The  so-called  "  Niirnberger  gold"  is 
an  aluminum  alloy  well  suited  for  artistic  objects, 
has  a  golden  color,  and  strongly  resists  atmospheric 
influences.  Its  composition  is  as  follows:  90  parts 


156  PRODUCTION  OF  ALUMINUM. 

copper,  2.5  parts  gold,  and  7.5  parts  aluminum. 
On  the  basis  of  its  specific  weight  it  belongs  rather 
in  the  category  of  heavy  alloys. 

Aluminum-platinum  Alloy. — This  was  first  pro- 
duced by  Margot,  assistant  at  the  University  of 
Geneva;  it  contains  28  parts  aluminum  and  72  parts 
platinum,  has  a  beautiful  yellow  color  which,  with 
certain  slight  variations  on  account  of  its  chemical 
composition,  takes  on  a  vivid  greenish  and  some- 
times copper-like  lustre,  is  brittle,  hard,  and  of 
crystalline  structure. 

Aluminum-palladium  Alloy  (Margot).  —  It  consists 
of  aluminum  and  palladium  in  proportions  such 
as  those  of  the  preceding  alloy,  has  a  beautiful 
rose  color  which,  as  soon  as  its  composition  is 
slightly  altered,  passes  over  into  steel-gray,  is  like- 
wise of  crystalline  structure,  brittle,  very  fragile, 
without,  however,  having  the  tendency  to  crumble 
gradually. 

Aluminum  -  cobalt  Alloy  (Margot). — It  contains 
aluminum  to  20-25%  and  cobalt  to  75-80%. 
Freshly  produced,  it  is  as  hard  as  hardened  steel, 
crystalline,  and,  like  the  alloys  just  described, 
crumbles  away  completely  upon  being  hammered. 
Even  after  a  few  days  it  falls  into  a  powder  of  a 
pronounced  violet-blue  tint. 

Aluminum-nickel  Alloy  (Margot). — 18%  aluminum, 
82%  nickel;  of  a  clear  straw-yellow  color;  almost 
as  hard  as  steel  and  capable  of  taking  a  high  polish. 
In  contrast  to  the  previous  alloys  it  may  be 


ALUMINUM  AND  ITS  ALLOYS.  157 

hammered  without  altering  its  constitution  in  any 
way. 

Ferro-silicon-aluminum  (Minet). — Under  this  classi- 
fication belong  alloys  having  the  following  com- 
position : 

Aluminum.  Iron,  Silicon. 

90  7  3  parts 

85  10  5     " 

80  14  6 

They  are  produced  directly  in  the  electric  furnace 
from  white  or  red  bauxite  or  from  a  mixture  of 
the  two,  and  are  successfully  used  in  metallurgy. 


(d)  Alloys  of  Various  Densities. 

Among  the  most  recent  investigations  of  the 
aluminum  alloys  we  shall  mention  the  researches 
of  Leon  Guillet  on  the  alloys  with  wolfram  and 
molybdenum,  then  the  researches  of  Boudouard 
on  magnesium-aluminum,  and  those  of  Edmond  Van 
Aubel  on  antimony-aluminum. 

Researches  of  L.  Guillet.* — This  investigator  has 
availed  himself  of  the  Goldschmidt  aluminothermic 
process  for  the  production  of  his  alloys.  His 
earliest  investigations  relate  to  the  reduction  of 
tungstic  acid,  molybdic  acid,  magnetic  iron  ore, 
manganese  monoxide,  and  titanic  acid  by  means 
of  aluminum  in  excess. 

*  L'Electrochimie,  June  1901,  pp.  86  and  89;  July,  p.  119. 


*5&  PRODUCTION  OF  ALUMINUM. 

We  shall  first  describe  the  results  which  Guillet 
has  obtained  in  the  reduction  of  tungstic  acid.* 
Neither  tungsten  nor  aluminum  must  be  present  in 
too  great  excess:  tungsten  must  not  be  present  in 
excess,  or  the  reaction  will  be  too  active ;  the  pres- 
ence of  aluminum  in  excess  would  prevent  the 
compound  from  being  enkindled.  A  mixture  which 
yields  AlioW  as  the  reaction-product  stands  just 
on  the  border-line  of  inflammability. 

Tests  in  which  the  composition  of  the  original 
material  is  so  selected  that  they  lead  theoretically 
to  alloys  of  the  formulas  AlWio  and  A15W  give 
a  metal  regulus  which,  treated  with  nitro -hydro- 
chloric acid,  leaves  behind  a  beautifully  crystallized 
residuum  with  the  composition  A1W2  (W  93.16%, 
Al  6.84%).  The  crystals  are  readily  affected  by 
concentrated  acids,  and  dissolved  by  boiling  water. 

Tests  in  which,  theoretically,  alloys  A1W  and 
AlioW  should  be  obtained  yield  numerous  lami- 
nated crystals  of  the  formula  A14W  (W  63.02%, 
Al  36.98%),  which  are  likewise  affected  by  con- 
centrated acids. 

Tests  which,  theoretically,  should  yield  alloys 
with  the  composition  A13W  and  A1W5  give  crys- 
tals which  at  the  surface  of  the  metallic  mass 
form  beautiful  excrescences,  and  for  which  we 
have  the  formula  A13W  (W  69.34%,  Al  30.66%). 
These  crystals  are  but  slightly  affected  even  by 

*  Compt.  rend,  de  1'Acad.  des  sciences,  May  6;  1901,  Paris. 


ALUMINUM  AND  ITS  ALLOYS.  159 

concentrated  acids;  they  disintegrate,  however  as, 
do  both  of  the  other  alloys,  in  boiling  water. 

Besides  tungsten-aluminum  L.  Guillet  succeeded 
in  producing  molybdenum-aluminum  *  as  well,  with 
the  aid  of  the  alumino-thermic  process:  six  com- 
pounds, indeed,  with  the  formulae  Al7Mo,  Al3Mo, 
Al2Mo,  AlMo,  AlMo4,  and  finally  an  alloy  very  rich 
in  molybdenum,  which  seems  to  have  the  composi- 
tion AlMo2o. 

Researches  of  Boudouard  f  on  Magnesium-aluminum 
Alloys.  J — In  the  year  1866  Wohler  began  to  attempt 
the  production  of  alloys  of  aluminum  and  mag- 
nesium, by  fusing  the  two  metals  together  with 
common  salt.  §  He  obtained  in  this  way  a  mixture 
which  produced  a  lustrous  tin-white  powder,  but 
without  any  perceptible  crystallization. 

Later  Parkinson  ||  succeeded  in  obtaining  a 
product  with  25%  of  magnesium,  by  melting  down 
both  metals  in  a  crucible  charged  with  pure,  fresh 
magnesia.  As  for  the  effect  of  the  magnesium  upon 
the  properties  of  the  alloy  in  question,  we  may  say, 
in  general,  that  a  percentage  of  magnesium  makes 
any  alloy  brittle  and  liable  to  crumble. 

Very  lately  Mach  has  produced  an  aluminum 
alloy  with  10-12%  of  Mg,  which  in  consequence  of 


*  Compt.  rend,  de  1'Acad.  des  sciences,  June  3,  1901,  Paris. 

t  L'Electrochimie,  June  1901,  p.  88. 

J  Compt.  rend,  de  1'Acad.  des  sciences,  June  3,  1901,  Paris. 

§  Annal   Ch.  Pharm.,  CXXXIII,  253. 

jj  Chemical  Society  (2),  Vol.  V,  p.  117. 


i6o 


PRODUCTION  OF  ALUMINUM. 


the  presence  of  the  latter  is  lighter  than  pure  alu- 
minum, is  of  a  silver  hue,  and  may  be  worked  in 
any  way  desired. 

Boudouard,  who  made  it  his  special  object  to 
determine  the  melting-point  of  the  different  alu- 
minum-magnesium alloys,  obtained  the  following 
results : 

TABLE  XIV. 

MELTING-TEMPERATURE    OF    THE    ALUMINUM-MAGNESIUM 
ALLOYS. 


Aluminum, 
Per  Cent. 

Magnesium, 
Per  Cent. 

Melting-point, 
Degrees  C. 

IOO 

O 

650 

90 

IO 

585 

80 

2O 

53° 

70 

30 

432 

60 

40 

45° 

5° 

5° 

462 

45 

55 

445 

40 

60 

45° 

35 

65 

455 

3° 

70 

424 

25 

75 

356 

20 

80 

432 

15 

85 

432 

10 

90 

437-5 

5 

95 

595 

0 

IOO 

635 

H  a  curve  is  constructed  with  weight-percentages 
of  aluminum  for  abscissae  and  the  melting-points  as 
ordinates,  it  is  seen  that  this  curve  has  two  maxima 
at  455°  and  462°  C.,  and  three  minima  at  356°, 
445°,  and  432°  C.  Between  10%  and  20%  alu- 
minum the  curve  is  clearly  parallel  with  the  axis 


ALUMINUM  AND  ITS  ALLOYS.  161 

of  the  abscissae.  The  two  maxima  express  the  two 
well-defined  compounds  AlMg2  and  AlMg. 

As  for  the  malleability,  only  alloys  with  a  per- 
centage of  aluminum  or  magnesium  not  higher 
than  0-15%  can  be  considered.  An  alloy  which 
consists  half  of  aluminum,  half  of  magnesium, 
crumbles  to  pieces  in  the  fingers,  and  may  be  pow- 
dered in  porcelain  mortars. 

Researches  of  E.  van  Aubel  on  Aluminum-anti- 
mony Alloys.* — An  alloy  whose  composition  is  ex- 
pressed in  the  formula  AlSb  melts  at  1078-1080°  C., 
while  the  pure  metals  melt  at  660°  and  430°  C. 
respectively.  Aubel  has  investigated  the  question 
whether  the  formation  of  this  peculiar  alloy  is  con- 
nected with  an  alteration  in  volume.  Tests  in 
which  two  pieces  with  known  percentages  of  alu- 
minum and  antimony  were  taken  at  different  places 
gave  a  complete  homogeneity  and  a  percentage 
composition  of  18.87%  A1  and  81.13%  Sb.  The 
density  of  this  alloy,  referred  to  the  vacuum  and 
to  water  at  4°  C.,  amounts  to  4.2176  at  a  tem- 
perature of  1 6°  C.  It  is,  therefore,  considerably 
smaller  than  we  might  theoretically  expect,  and  it 
follows  that  with  the  formation  of  the  alloy  a  very 
considerable  increase  in  volume  takes  place.  We 
have  here,  then,  an  exception  to  the  Matthiesen  law. 
We  may  also  formulate  the  result  more  clearly, — • 
that  7.07  cm3  aluminum  + 12.07  cm2  antimony  give 
23.71  cm3  of  the  alloy  AlSb. 

*  L'Electrochimie,  September  1901,  p.  136. 


162 


PRODUCTION   OF  ALUMINUM. 


(e)  Light  Alloys. 

Under  this  heading  belong  a  great  number  of 
alloys,  which  are  classified  as  "  light "  because  their 
density  does  not  differ  materially  from  that  of 
aluminum,  since  they  contain,  at  most,  6%  of  their 
weight  in  heavy  metals. 

Copper-aluminum  Alloys.  —  Their  percentage  of 
copper  varies  between  3  and  6%.  Table  XV  repro- 
duces the  test  results  which  were  obtained  by 
Charpentier-Page  in  two  extreme  cases. 


TABLE  XV. 
Aluminum  97%,  Copper  3. 

ANNEALED    WIRE. 

2  mm  in  diam.     Density  2.737. 
Electrical  Tests. 

Resistance  per  metre 0.01141/2 

Resistance  per  mm2  cross-section  and  per  km 35  .83/2 

Resistance  of  a  copper  wire  of  the  same  dimensions, 

at  22°  C 17.9/2 

Proportion  of  conductivities 49  . 99% 

Mechanical  Tests. 


i 

2 

3 

Length  of  test-piece  mm 

I  IO 

I  IO 

I  IO 

Elongation                                          '  ' 

22      C 

23     C 

2  C 

Elasticity.                                           kg 

64.    c 

64.     S 

6  e    i  o 

Elasticity   per  mm2   cross-sec- 
tion                               " 

20   54 

2O     38 

20    76 

Elongation  % 

21      3 

21      3 

21    7 

Test. 


ALUMINUM  AND  ITS  ALLOYS. 


163 


HARD    WIRE. 

2  mm  in  diam.     Density  2.742. 
Electrical  Tests. 

Resistance  per  metre o.oi  145/2 

Resistance  per  mm2  cross-section  and  per  km 35  .96/2 

Resistance  of  a  copper  wire  of  the  same  dimensions, 

at  22°  C 17.9/2 

Proportion  of  conductivities 49-77% 

Mechanical  Tests. 

Test. 

123 

Length  of  the  test-piece mm  no  no  no 

Elongation "  5  4                 4.5 

Elasticity kg  no  in  109 

Elasticity  per  mm2  cross-sec- 
tion      '  35.3  35.3           34.7 

Elongation %  4.5  3.6            4 

Aluminum  94%,  Copper  6%. 

ANNEALED    WIRE. 

2  mm  in  diam.      Density  2.818. 
Electrical  Tests. 

Resistance  per  metre.  .  ... 0.01025/2 

Resistance  per  mm2  cross- section  and  per  km 37 .8i/2 

Resistance  of  a  copper  wire  of  the  same  dimensions, 

at  i9°C 17.6/2 

Proportion  of  conductivities 46 . 5% 

Mechanical  Tests. 

Test. 

I  2  3 

Length  of  test-piece mm  105  105  105 

Elongation '  17  19  21 

Elasticity kg         78  75  73.5 

Elasticity    per  mm2   cross-sec- 
tion     '  24.8  23.8  22.4 

Elongation    %          16.2  18  20 


164 


PRODUCTION   OF  ALUMINUM. 


HARD    WIRE. 

2  mm  in  diam.      Density  2.827. 
Electrical  Tests. 

Resistance  per  metre 0.0129/1 

Resistance  per  mm2  cross-section  and  per  km 40 .  51/2 

Resistance  of  a  copper  wire  of  the  same  dimensions, 

at  19°  C 17.6/2 

Proportion  of  conductivities 43  .44% 

Mechanical  Tests. 


Test. 


i 

2 

3 

Length  of  test-piece 

mm 

IOC 

I  O6 

IOC 

Elongation 

•2 

2     C 

Elasticity 

kg 

142 

I  -2  e 

I  3  C 

Elasticity  per  mm2 
tion           

cross-sec- 

4$    2 

42    Q 

42    Q 

Elongation  

,     % 

2    8 

2     1 

2     8 

A  simple  calculation,  quite  like  that  which  we 
have  made  for  pure  aluminum,  shows  the  advantage 
of  using  conducting  wire  of  copper-aluminum  rather 
than  pure  copper,  although  the  alloy  in  question  is 
a  somewhat  poorer  conductor  than  pure  aluminum, 
and  is  only  half  as  good  as  pure  copper. 

Copper-aluminum  is  in  many  cases  preferred, 
in  industry,  to  pure  aluminum,  because  of  its 
excellent  mechanical  properties. 

Nickel  -  aluminum,  Nickel  -  copper  -  aluminum,  or 
German  -  silver  -  aluminum  (Tissier,  Le  Verrier,  and 
especially  A.  E.  Hunt,  technical  director  of  the 
Pittsburg  Co.). — The  alloys  named  contain  only 
about  3%  of  heavy  metals.  Nickel  imparts  to  the, 


ALUMINUM  AND  ITS  ALLOYS.  165 

aluminum  a  certain  stiffness,  and  gives  an  alloy 
which  may  be  easily  worked  or  made  into  plates, 
and  whose  mechanical  properties  are  about  the 
same  as  those  of  copper-aluminum. 

Joseph  Richards  has  found  that,  of  all  aluminum 
alloys,  nickel-aluminum  and  nickel-copper-alumi- 
num best  withstand  chemical  influences.  He  has 
exposed  a  great  number  of  alloys  to  the  effect  of 
hydrochloric  acid,  nitric  acid,  acetic  acid,  potash- 
lye,  and  sodium  chloride,  and  has  drawn  up  the 
following  table,  in  which  the  alloys  are  arranged 
in  groups  according  to  their  increase  in  stability. 

HCl.  NH03. 

Titanium-aluminum  Aluminum,  pure 

Aluminum,  pure  Titanium-aluminum 

Copper-aluminum  Copper-aluminum 

German-silver-aluminum  Nickel-aluminum 

Nickel- aluminum  German-silver-aluminum 

C2H4O2.  KOH. 

Aluminum,  pure  Aluminum,  pure 

Titanium- aluminum  Titanium-aluminum 

Copper- aluminum  Copper-aluminum 

German-silver-aluminum.  Nickel-aluminum 

Nickel-aluminum  German-silver-aluminum 

NaCl. 

Aluminum,  pure 
German-silver-aluminum 
Titanium-aluminum 
Copp  er-  aluminum 
Nickel-  aluminum 

The  German  silver  here  used  is  the  so-called 
"type  de  la  guerre,"  with  the  composition;  80% 

Cu,  20%  Ni, 


166  PRODUCTION   OF  ALUMINUM. 

Nickel-tin-aluminum. — Of  this  alloy  three  differ- 
ent lots  were  tested: 

No.  i:  85  parts  aluminum,  15  parts  tin,  2  parts  nickel 
No.  2:  90  ,  10       "        "  ,  3       " 

No.  3:  90  ,11  "  ,  4 

These  alloys  he  finds  much  harder  than  alumi- 
num and  easier  to  work  with  the  file;  moreover, 
they  may  be  soldered  directly  with  one  another  or 
with  aluminum  and  other  metals.  The  solder  con- 
tains either  4  parts  silver,  8  parts  zinc,  and  5  parts 
tin,  or  else  5  parts  silver,  8  parts  zinc,  and  5  parts 
tin. 

Nickel-iron-aluminum.  —  Composition :  90  parts 
aluminum,  4  parts  nickel,  i  part  iron,  or  85  parts 
aluminum,  10  parts  tin,  4  parts  nickel,  and  2  parts 
iron.  These  alloys  may  without  difficulty  be 
worked  with  the  file,  and  may  be  easily  rolled; 
they  break  in  pieces,  however,  under  the  hammer. 

Cobalt-aluminum.  —  With  a  proportion  of  6%  of 
cobalt  this  alloy  may  be  easily  rolled  into  plates. 

Manganese-aluminum.  —  Michel  obtains  an  alloy 
of  this  kind  by  melting  together  2  parts  manganese 
protochloride,  6  parts  potassium-sodium  chloride, 
and  4  parts  aluminum.  If  the  metal  mass  is  treated 
with  hydrochloric  acid,  an  insoluble  part  remains, 
having  a  density  3.4,  whose  composition  is  ex- 
pressed in  the  formula  MnAl3. 

Manganese-copper-zinc-aluminum. — The  analysis  of 
alloys  of  this  sort  which  were  produced  by  Susini 
gave: 


No.  i  .  .  . 

.   07 

JO 

No.  2  .  .  . 

.  08 

1-5 

No   * 

.     02 

2-£ 

No.  A. 

.     00 

IO 

ALUMINUM  AND  ITS  ALLOYS.  167 

Aluminum.     Manganese.     Copper.  Zinc. 

1-5  o-S 

2.5  i 

4-5  1-5 


Titanium-aluminum  (Wohler,  Michel,  Levy).  - 
Michel  produced  an  alloy  of  the  formula  Al3Ti,  which 
contained,  accordingly,  35%  of  titanium.  An  alloy 
with  70%  of  titanium,  examined  photomicro- 
graphically,  gave  peculiar  results:  it  appeared 
as  if  slashed  with  sword-cuts.  An  alloy  with 
3%  of  titanium  is,  according  to  Brown,  almost  as 
hard  as  iron. 

Tungsten-aluminum.  —  This  alloy  also  originates 
with  Michel.  Its  proportion  of  aluminum  and  of 
tungsten  is  expressed  in  the  formula  AlsWo. 

The  following  table  gives  some  test-results  ob- 
tained by  Le  Verrier  with  an  alloy  containing 
7.5%  of  tungsten: 

.     Elasticity       Percentage  of 
per  mm2.         Elongation. 

Metal,  cast 15. 5  kg  i .  5% 

"       rolled,  hardened 25  4% 

"       annealed 18       "          10% 

'*  "  rf     r»     "  T  A  O7 

I5  -9  I4/o 


Reinhard  and  Isidor  Roman  recommend  an  alloy 
containing  tungsten  which  they  call  wolframinium, 
and  which  contains  0.75  part  copper,  0.105  part 
tin,  1.442  parts  antimony,  0.0388  part  tungsten. 


i6S  PRODUCTION  OF  ALUMINUM. 

and  98.04  parts  aluminum.     Its  mechanical  prop- 
erties may  be  seen  from  the  following  figures: 

Elasticity      Percentage  of 
per  mm2.          Elongation. 

Metal,  hardened 38 . 7  kg         2 . 14% 

annealed 26.5    "        15.24% 

Partinium.  —  This  alloy,  the  name  of  which  is 
derived  from  that  of  the  discoverer,  G.  H.  Partin, 
is  obtained  in  the  following  manner :  First,  a  mix- 
ture of  78  parts  copper,  20  parts  tin,  and  2  parts 
potassium  arsenate  .is  melted;  the  alloy  ob- 
tained is  then  powdered,  and  with  it  are  mixed  i 
part  tungsten  and  3  parts  antimony.  The  whole 
is  thereupon  melted  again,  pulverized,  and  added  to 
aluminum,  which  is  alloyed,  up  to  4%,  with  this 
metallic  mixture.  Tungsten  and  antimony  may 
here  be  replaced  by  an  equal  weight  of  powdered 
magnesium. 

As  a  solder  for  partinium  the  inventor  recom- 
mends a  mixture  of  60  parts  zinc,  30  parts  tin, 
4  parts  nickel,  and  4  parts  copper,  which  are  melted 
with  2  parts  potassium  arsenate. 

Zinc-aluminum. — Hard,  but  brittle. 

Cadmium-aluminum.  —  Quite  capable  of  elonga- 
tion; its  particular  use  is  as  a  solder-metal. 

Bismuth-aluminum. — With  a  percentage  of  more 
than  i  %  of  bismuth,  it  is  brittle  and  fragile. 

Antimony-aluminum. — According  to  D.  A.  Roche 
aluminum  is  alloyed  with  antimony  easily  and  in  all 


ALUMINUM  AND  ITS  ALLOYS.  169 

proportions.  Alloys  with  a  slight  percentage  of 
antimony  (below  5%)  are  harder,  more  tenacious, 
more  elastic,  and  at  the  same  time  more  mal- 
leable than  pure  aluminum.  Although  with  an 
increase  in  the  proportion  of  antimony  the  hard- 
ness increases,  the  tenacity  and  the  elasticity  de- 
crease very  rapidly,  and  the  alloy  is  readily 
pulverized. 

Silicon-aluminum. — These  alloys  are  always  more 
or  less  ferruginous ;  with  1-2  %  of  iron  the  strength 
increases  with  an  increase  in  the  proportion  of  sili- 
con, and  soon  reaches  23-25  kg  per  mm2  with  an 
elongation  of  10%.  Unfortunately  these  alloys  are 
strongly  attacked  in  air,  as  well  as  by  most  chemi- 
cal reagents. 

Silver-aluminum.  —  With  5%  of  silver  this  alloy 
is  said  to  be  just  as  malleable  as  the  pure  metal. 
Carrol  produces  an  alloy  with  90-93  parts  aluminum, 
6-9  parts  silver,  and  i  part  copper  which,  it  is  said, 
may  be  advantageously  used  for  engravings.  The 
addition  of  copper,  according  to  the  statement  of 
the  inventor,  appears  to  give  the  metal  a  denser 
grain.  With  from  10%  of  silver  upwards,  the 
alloy  is  brittle;  under  the  name  of  "tiers-argent  " 
there  has,  however,  been  obtained  an  alloy  of  f 
aluminum  and  J  silver,  which  is  said  to  permit  of 
being  stamped  and  engraved  more  readily  than 
copper-silver  alloys. 

Tin-aluminum  is  chiefly  of  consequence  in  con- 
nection with  the  manufacture  of  solder.  Bour- 


iyo 


PRODUCTION   OF  ALUMINUM. 


bouze  recommends  an  alloy  with  10%  of  tin,  which 
is  said  to  be  soldered  just  as  readily  as  brass;  he 
employs  it  to  advantage  for  physical  apparatus, 
since  its  coefficient  of  expansion  is  lower  than 
that  of  pure  aluminum.  At  the  same  time,  Riche 
shows  that  alloys  of  tin  and  aluminum  are  more 
readily  attacked  than  either  metal  by  itself.  Its 
elasticity  is  less  than  that  of  pure  aluminum,  as 
appears  from  the  following  table: 


Composition  of  the  Metal. 

Method 

Elasticity 
per  mm* 

Elongation 

Aluminum, 

Silicon, 

Iron, 

Tin, 

of 
Working. 

Cross- 
section. 

in 
Per  Cent. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

88 

J-35 

O  .65 

IO 

cast 

9.80 

4.  II 

48.9 

0.72 

0.36 

5° 

forged 

IO  .6l 

0.08 

With  respect  to  ductility  also,  the  alloy  is  inferior 
to  the  unalloyed  metal. 

Le  Verrier  has  made  tests  to  determine  how  the 
melting-point  of  tin-aluminum  varies  with  the 
percentage  of  tin. 


Composition  of  the  Metal. 


Aluminum, 
Per  Cent. 

Silicon, 
Per  Cent. 

Iron, 
Per  Cent. 

Tin, 
Per  Cent. 

point, 
Degrees  C. 

90 

1-4 

o  .  70 

8 

595 

78.2 

I  .  2 

o  .60 

20 

575 

68.4 

1-05 

0-53 

30 

535 

58-7 

o  .90 

0-45 

40 

575 

48.9 

°-75 

0.38 

5° 

57° 

19  .6 

0.30 

o.iS 

80 

530 

9.8 

°-*S 

o  .07 

90 

49° 

Melting- 


WORKING  OF  ALUMINUM.  171 

From  this  table  it  follows  that  the  melting-point 
is  rather  independent  of  the  composition  of  the 
alloy,  at  least  up  to  a  proportion  of  80%  of  tin. 
With  90%  of  tin,  however,  it  always  remains  at 
490°  C. 

Chromium-aluminum. — Wohler  obtained  an  alloy  of 
this  kind  by  reducing  the  violet  chromium  chloride 
by  means  of  aluminum;  there  is  a  metal  regulus 
whose  composition  is  approximately  expressed  by 
the  formula  AlCr.  If  the  alloy  is  to  be  hammered 
and  rolled,  the  proportion  of  chromium  should  not 
exceed  3%. 

Quicksilver-aluminum.  —  According  to  Bailie  and 
Fery  we  have  here  a  compound  Al2Hg3.  The 
higher  the  temperature  with  which  one  works,  the 
more  readily  the  amalgam  is  obtained.  While  at 
100°  the  reaction  is  extremely  sluggish,  the  two 
metals  unite  very  quickly  at  the  boiling-point  of 
quicksilver.  According  to  Krouchkoll  the  alloy 
is  readily  oxidizable. 

C.  WORKING  OF  ALUMINUM. 

We  may  say,  in  general,  that  aluminum  may  be 
worked  as  copper  is  worked,  and  with  the  same 
tools,  but  with  more  difficulty.  We  will,  however, 
add  just  here  that,  despite  countless  experiments,  no 
easily  applicable  solder  for  aluminum  has  yet  been 
found,  and  also  that  the  proposed  processes  for 
coppering,  silvering,  and  gilding  have  not  been 
conclusively  tested. 


172  PRODUCTION  OF  ALUMINUM. 

As  for  the  melting-  and  the  casting-process, 
aluminum  is  melted  dry,  that  is  to  say,  with  no 
flux,  in  clay  or  graphite  crucibles,  and  during  the 
melt  metal  is  constantly  added.  When  the  mass  is 
completely  molten,  it  is  brought  to  a  red  glow,  and 
the  crucible  is  removed  from  the  fire.  The  metal 
is  now  violently  stirred  by  means  of  an  iron  rod, 
which  ends  in  a  small,  round  ladle  at  a  right  angle 
to  the  rod  and  perforated;  the  surface  of  the  melt 
is  skimmed  and  the  layer  of  oxide  formed  is  re- 
moved, whereupon  the  true  operation  of  casting 
begins.  The  stirring-rod  is  removed  from  the  melt 
as  soon  as — without  as  yet  being  at  a  red  glow — it 
is  so  hot  that  the  metal  does  not  adhere  to  it. 

Since  the  aluminum  as  it  stiffens  shrinks  quite 
perceptibly — about  1.8% — during  the  stiffening, 
according  to  the  amount  of  contraction,  molten 
metal  should  be  cautiously  added  in  as  small  quan- 
tities as  possible,  in  order  to  keep  the  mold  well 
filled.  For  the  casting-mold  metal  vessels  may  be 
used;  complicated  objects  it  is  advisable  to  cast  in 
sand. 

Pure  aluminum,  as  well  as  that  of  commerce  with 
98.5%  of  aluminum,  may  be  forged,  drawn,  and 
rolled  cold,  without  necessarily  being  annealed 
beforehand.  With  97%  aluminum  and  a  prepara- 
tion of  3%  of  heavy  metals  and  silicon  it  may  like- 
wise be  forged  and  rolled  cold,  but  only  after  it  has 
been  repeatedly  subjected  to  an  annealing  process. 
It  is  preferable  under  these  conditions  to  work  the 


WORKING  OF  ALUMINUM.  173 

metal  heated  to  a  temperature  approximating  200°  C. 
If  the  aluminum,  on  the  other  hand,  contains  more 
than  5%  of  foreign  elements  (including  silicon), 
it  can  only  be  worked  in  the  heat.  With  i%  of 
heavy  metals  present  it  may  be  rolled  provided  the 
proportion  of  silicon  is  10-15%. 

It  is  generally  not  best  to  heat  the  metal  higher 
than  to  350°  or  400°  C.  during  or  at  the  beginning 
of  the  treatment ;  indeed,  it  may  well  be  kept  some- 
what below  this  temperature,  and  heated,  if  neces- 
sary, higher  in  some  parts;  while  the  other  parts, 
according  to  the  mode  of  the  further  treatment, 
remain  outside  of  the  fire  or  between  two  iron 
plates,  and  may  eventually  be  cooled. 

As  an  example  of  the  way  in  which  aluminum 
may  be  worked  by  means  of  the  wooden  anvil 
and  wooden  hammer,  especially  in  ship-building, 
we  may  cite  the  pleasure-yacht  "  Vendenesse," 
belonging  to  Count  J.  de  Chabannes  la  Palice,  in 
whose  bottom  and  rudder-post  aluminum  was 
used  extensively.  This  vessel  was  built  by  Godinot 
after  the  plans  of  Victor  Guilloux;  for  metal  a 
3%  copper-aluminum  alloy  was  employed,  which 
was  forged  and  worked  cold,  and  was  found  to 
answer  very  well.  The  thickness  of  the  aluminum 
plates  was  2-4  mm. 

The  adaptation  of  the  plates  for  the  bottom 
appears  wholly  similar  to  what  it  would  be  in  the 
case  of  copper  plates.  Here,  too,  the  metal  is 
worked  cold  with  the  wooden  mallet.  It  preserves 


174  PRODUCTION  OF  ALUMINUM. 

the  shape  given  to  it  without  deformation ;  for  pieces 
with  sharp  curves  and  bulgings  it  is  best  to  take  an 
aluminum  that  is  but  slightly  alloyed.  Aluminum 
is  soft,  like  copper,  and  like  copper  may  be  bored 
without  difficulty;  it  is,  however,  desirable  to  use 
tools  as  sharp  as  possible,  and  to  oil  them  before 
use  with  petroleum  or  turpentine-oil. 

Nor  is  there  any  difficulty  in  the  riveting;  the 
plates  may  receive  a  hard  hammering  without  being 
split,  do  not  turn,  stay  straight,  and  do  not  hollow 
out  at  the  rivet-holes,  so  that  the  rivets  hold  well 
even  in  millings.  At  most,  since  it  is  very  malleable, 
the  metal  occasionally  shows  a  tendency  to  bulge 
out  a  trifle  where  the  rivets  come  too  near  the 
edge.  When  the  rivets  have  once  been  driven  in 
it  is  difficult  to  remove  them,  even  with  the  pliers; 
they  are  generally  considered  weaker  than  iron, 
but  are  placed  nearer  together. 

Aluminum  may  be  filed  and  grooved  like  red 
copper,  to  which  in  fact  it  is  similar,  indeed,  in 
many  respects,  except  that  in  case  it  is  desired  to 
harden  the  metal  one  must  take  the  precaution  to 
work  it  cold  in  so  far  as  possible,  after  repeated 
annealing.  Alloyed  and  hammered,  it  may  perfectly 
well  be  turned  and  planed  if  the  instruments  are 
sufficiently  sharp  and  work  at  sufficient  speed. 
The  latter  are  lubricated  with  turpentine-oil  or 
petroleum,  or,  better  still,  with  suds — in  no  event, 
however,  with  oil.  The  work  of  milling  proceeds 
smoothly.  When  the  cutters  become  clogged,  as 


WORKING  OF  ALUMINUM.  175 

frequently  happens,  they  must  be  cleansed  with 
oil  and  a  brush. 

Aluminum  takes  a  high  polish,  but  the  lustre 
is  not  white,  as  in  the  case  of  silver  or  nickel,  but 
bluish,  as  with  tin.  Certain  alloys  in  particular 
show  these  hues  very  clearly.  The  pieces  are  first 
scoured  with  pumice-stone,  and  then  polished  with 
brushes  which  have  a  paste  rubbed  upon  them. 
The  latter  consists  of  half-powdered  emery,  which 
is  mixed  with  tallow  and  formed  into  small  pellets. 
The  polishing  is  finally  completed  with  polishing- 
soap  and  turpentine-oil. 

The  pure  metal,  annealed,  bends  very  readily, 
is  easily  chased,  but  does  not  harden  so  well,  and 
possesses  when  it  has  been  worked  but  little  stiffness ; 
the  alloys,  on  the  contrary,  particularly  with  6% 
of  copper,  have  an  unusually  great  resistance  even 
when  chased,  but  are  harder  to  work.  If,  however, 
the  material  permits  of  being  heated  to  ioo°- 
150°  C.,  the  treatment  is  thereby  made  considerably 
easier.  The  treatment  when  cold  should  be  made 
as  brief  as  possible,  in  order  not  to  keep  the  alloy 
too  long  under  .at  a  tension. 

Processes  for  Soldering  Aluminum. 

A  great  many  processes  have  been  devised  for 
soldering  aluminum  with  itself  or  with  another 
metal;  it  would  appear,  however,  that  up  to  the 
present  time  no  truly  practical,  simple,  and  well- 
tested  method  has  been  devised.  One  may  set 


176  PRODUCTION  OF  ALUMINUM. 

about  the  operation  in  two  different  ways:  either 
by  uniting  the  surfaces  to  be  soldered  by  means 
of  a  special  solder, — hence  by  means  of  an  easily 
melted  alloy, — or  again  by  a  process  of  so-called 
autogenous  soldering,  in  which  the  addition  of  any 
foreign  metal  or  of  an  alloy  is  avoided.  As  a  rule, 
the  first  process  is  employed. 

First  Process. — Of  the  large  number  of  receipts 
and  prescriptions  coming  under  this  heading  we 
shall  here  cite  only  the  most  important. 

i.  Dr.  Edward  D.  Self  writes  in  the  "  Moniteur 
scientifique"  (1887)  as  follows:  "The  great  difficulty 
in  uniting  two  pieces  of  aluminum  is  due  to  the  fact 
that  at  the  place  of  soldering  an  extremely  thin 
film  of  alumina  is  formed,  which  resists  the  union 
of  the  metal  with  the  solder  in  question."  With 
the  exercise  of  great  care,  however,  according  to 
the  statement  of  Self,  good  results  should  be  ob- 
tained with  the  following  alloy: 

Type  i :  i  part  silver,  2  parts  aluminum. 

Type  2:  85-95  parts  tin,   15-5  parts  bismuth. 

Type  3:  99  parts  tin,  i  part  bismuth;  with  the 
addition  of  i  part  aluminum  the  strength  of 
this  solder  is  much  increased. 

Type  4:  90  parts  tin,  5  parts  bismuth,  5  parts 
aluminum. 

The  two  pieces,  well  cleansed,  are  first  carefully 
warmed  a  little,  and  the  solder  is  then  put  on  by 
means  of  a  soldering-iron,  vaseline  or  paraffine 
serving  as  a  flux. 


WORKING  OF  ALUMINUM.  177 

2.  Mourey  (1859)  gives  the  following  receipts: 
Type   5 :  80  parts  zinc,  20  parts  aluminum. 

"       6:  85      "         "      15      " 

"       7:  88      "         "      12      " 

"       8:  92      "         "        8      " 

11  9:  94  "  "  6  " 
For  the  production  of  this  solder,  first  aluminum 
is  melted,  and  then  zinc  is  added  bit  by  bit  with 
constant  stirring.  The  soldering  itself  is  done 
with  a  soldering-iron;  the  soldering-surfaces  are 
moistened  with  a  composition  of  3  parts  Copaiba 
balsam,  i  part  Venetian  turpentine-oil,  and  a  few 
drops  of  a  weak  mineral  or  plant  acid  (phosphoric 
acid,  uric  acid),  and  the  zinc,  during  the  whole 
operation,  is  protected  as  far  as  possible  from 

oxidation. 

> 

3.  Bourbouze  (1866)  solders  aluminum  by  tinning 
the    surfaces    which    are   to   be    joined.     For    this 
purpose,  instead  of  employing  tin  alone,  he  makes 
use  of  various  alloys  of  tin  with  zinc,  with  bismuth 
and    aluminum,    and    with    aluminum    alone;     the 
latter  alloy  he  considers  the  best;    the  quantity  of 
both  constituents  alters  according  to  the  method 
of  the  further  treatment  of  the  material  in  ques- 
tion. 

The  solder 

Type  10 :    10  parts  aluminum,   44  parts  tin 
is  especially  recommended.      It  is  sufficiently  malle- 
able to   permit   of    being  worked    with   the   ham- 
mer;   pieces  soldered  in  this  way  may  be  planed 


178  PRODUCTION   OF  ALUMINUM. 

and  turned.  If,  however,  the  objects  are  not  to  be 
exposed  to  any  further  treatment,  a  soft  solder  which 
contains  less  aluminum  is  suitable. 

For  the  tinning  itself,    Bourbouze  indicates  no 
special  precautions. 

4.  A  solder  with  the  following  composition  is  said 
to  give  very  satisfactory  results: 

Type  11:5  parts  zinc,  2  parts  tin,  i  part  lead. 

5.  In  the  section  that  treats  of  light  alloys  we 
have   given   some   receipts   for   the   production   of 
soldering-metals  which  we  shall  here  repeat. 

For  nickel-tin-aluminum  alloys  are  used 

Type    12:  4  parts   silver,    8   parts   zinc,    5   parts 

tin  (soft  solder),  and 
Type   13:  5   parts  silver,   8  parts  zinc,    5   parts 

tin  (hard  solder). 
For  partinium: 
Type   14:  60   parts   zinc,    30   parts  tin,    4  parts 

nickel,  4  parts  copper  melted  with  2  parts 

potassium  arsenate. 

6.  Charpentier-Page     has     commercially     intro- 
duced two  kinds  of  soldering-metal : 

Type   15:  48  parts  tin,   27  parts  zinc,   23  parts 

lead,  2.25  parts  aluminum; 
Type   16:  40  parts  tin,  100  parts  zinc,  20  parts 

lead; 

and  he  gives  the  following  instructions  for  their 
use:  The  parts  are  steamed  with  potash  and 
polished,  in  order  to  keep  the  surfaces  perfectly 
smooth  and  free  from  grease;  the  soldering-iron 


WORKING  OF  ALUMINUM.  179 

is  cleansed  with  the  file  and  smeared  with  sal- 
ammoniac;  if  it  is  tinned,  merely  the  filing  away 
is  sufficient.  The  surfaces  to  be  soldered  must 
not  be  moistened  with  nitric  acid  nor  with 
any  other  reagent;  they  are  first  tinned  with 
one  of  the  above-named  alloys  applied  to  each 
other,  and  then  soldered  as  usual  with  the  soldering- 
iron.  When  the  surfaces  have  once  been  tinned 
with  the  Charpentier-Page  metal,  the  usual  tin- 
solder  also  holds  very  well.  Charpentier-Page  has 
by  his  process  even  soldered  tubes  of  considerable 
length. 

7.  Novel  (Geneva)  produces  soldering-metals  with 
strong  resistance,  whose  composition  and  method  of 
production  are,  however,  kept  secret  by  the  inventor. 
It  is  worthy  of  note  that  in  three  out  of  four  tests 
for  strength  held  at  the  "  Conservatoire  des  arts  et 
metiers"  there  was  no  tearing  away  at  the  place  of 
soldering. 

8.  Wagner  recommends  the   following  composi- 
tion: 

Type  17:  100  parts  tin,  165  parts  lead,  9  parts  zinc. 

9.  According  to  Lejcal  the  following  alloy  gives 
good  results: 

Type  18:    2  parts  tin,  5  parts  zinc,   i  part  lead. 

10.  J.    W.    Richards,    in    the    "  Journal    of    the 
Franklin  Institute"  (1896),  publishes  the  following 
data: 

Type  19:    i  part  aluminum,   i  part  phosphorus- 
tin  (10%),  8  parts  zinc,  32  parts  lime. 


l8o  PRODUCTION  OF  ALUMINUM. 

Type  20:  2.38  parts  aluminum,  78.34  parts  tin, 
19.04  parts  zinc,  0.24  parts  phosphorus. 

Type  21 :  2.38  parts  aluminum,  71.12  parts  tin, 
26.19  parts  zinc,  0.24  parts  phosphorus. 

Richards  has  observed  that  at  the  moment  of 
transition  into  the  molten  state  with  these  alloys 
an  easily  melted  compound  having  the  composi- 
tion 4  parts  tin  and  3  parts  zinc  is  separated  off, 
which  seems  to  be  more  durable  and  solders 
better. 

ii.  P.  d'Arlatan,  in  the  "  Chronique  Industrielle" 
of  December  15,  1900,  has  published  a  number  of 
patented  receipts  for  the  production  of  soldering- 
metals:  the  first  is  the  one  proposed  by  S.  Tailor 
in  Birmingham. 

Type  22:  4  parts  aluminum,  12  parts  silver, 
4  parts  copper,  8  parts  zinc,  12  parts  lead 
or  cadmium,  60  parts  tin. 

Silver  is  melted  in  a  graphite  crucible,  and  there- 
upon the  other  metals  are  added  successively,  in 
the  order  given,  while  the  whole  is  kept  constantly 
stirred  by  means  of  a  steel  rod. 

Type  23:   30  parts  tin,  50  parts  cadmium. 

This  solder,  which  is  of  the  consistency  of  dough, 
is  rubbed  upon  the  previously  warmed  object  of 
aluminum  by  means  of  a  piece  of  asbestos;  the 
soldering  then  proceeds.  In  quite  the  same  way 
are  handled  also  alloys  of  tin-zinc  and  of  tin-zmc- 
cadmium  (English  patent  No.  8406).  If  a  solder- 
ing-pipe  is  at  hand,  common  soldering-metal  may 


WORKING  OF  ALUMINUM.  l8l 

also  be  used,  with  chloride  of  silver  for  the  flux. 
Chloride  of  silver  alone  may  also  be  used,  if  it  is 
applied  powdered  to  the  surfaces  to  be  soldered 
after  they  have  been  well  steamed;  the  soldering 
then  proceeds  as  usual. 

It  is  further  proposed,  in  the  publication  cited, 
first  to  tin  the  aluminum  with  an  alloy  of  the 
composition : 

Type  24:  i  part  aluminum,  5  parts  tin, 
and  then  to  solder  with  the  same  mixture. 

12.  Vevey's  "  Science  Pratique"  recommends: 
Type  25:     45    parts    aluminum,    70    parts    zinc, 

15  parts  copper. 

13.  L.  G.  Delamothe,  chemist,  in  New  York,  pro- 
duces a  metal,  according  to  "  Nature,"  which  con- 
tains 

Type  26:    1 60  parts  tin,  40  parts  zinc,   10  parts 

britannia,   10  parts  silver. 

By  ' '  britannia  ' '  is  understood  an  alloy  containing 
100  parts  tin,  8  parts  antimony,  and  2  parts 
copper.  Directly  before  the  cast  the  crucible  is 
removed  from  the  fire,  and  i  g  of  phosphorus  is 
added,  while  a  stirring  is  kept  up,  by  means  of 
an  iron  rod,  till  the  phosphorus  is  completely 
consumed.  The  alloy  is  then  cast  in  bars,  with 
which  the  parts  to  be  soldered  are  tinned;  the 
soldering  itself  may  be  undertaken  either  with 
the  same  alloy  or  with  common  solder,  with 
the  aid  of  a  solder-pipe  or  soldering-iron.  The 
surfaces  must  previously  be  brushed  off,  an<J 


1 82  PRODUCTION  OF  ALUMINUM, 

thoroughly     cleansed     with     rosin     dissolved     in 
stearin. 

14.  Professor    C.    D.   Thiving    of    Knox    College 
recommends   an   alloy   of   zinc,    tin,    and   bismuth, 
which  melts  at  a  very  low  temperature  and  may 
therefore  be  conveniently  handled  with  the  soldering- 
iron.     It  is  affected  neither  by  water  nor  by  damp 
air,  and  as  regards  mechanical  resistance  is  scarcely 
inferior  to  aluminum. 

15.  Gaston    Tissandier,    in    his    "  Recettes    and 
Precedes  utiles,"   refers   to   the  fact  that  if  both 
metals  are  previously  coppered  galvanically,  or  by 
some   other   means,    the   soldering   may   easily   be 
effected,  even  by  the  ordinary  means,  except  that 
the  greatest  care  must  be  taken  to  see  that   the 
copper  coating  melts  or  separates  off.     As  regards 
the   coppering,    Tissandier   remarks   that   in   cases 
where  it  is  impracticable  to  immerse  the  parts  to 
be  soldered  directly  in  a  copper  bath,  very  good 
results  may  be  obtained  by  the  use  of  blotting- 
paper  saturated  with  copper  sulphate.     As  soon  as 
the  contact  of  the  paper  with  the  surface  in  ques- 
tion and  with  a  piece  of  copper  has  been  brought 
about,  the  positive  pole  of  a  battery  is  connected 
with  the  latter,   while   the   negative   pole   is   con- 
nected with  the  aluminum  object,  and  after  a  short 
time  a  firm  coating  of  copper  is  obtained  on  the 
surface  to  be  soldered.     A  mixture  of  rosin,   tal- 
low,   neutral    zinc    chloride,    and   quicksilver   sub- 
limate is  also  said  to  serve  the  purpose  well.     A  suit- 


WORKING  OF  ALUMINUM. 


183 


able  solder  will  be  found  in  an  alloy  of  the  com- 
position : 

Type  27:  52  parts  copper,  46  parts  zinc,  2  parts 
tin,  with  borax  for  the  flux. 

1 6.  In  his  "  Recueil  des  procedes  modernes" 
Marcel  Bourdais  gives  more  than  twelve  different 
methods  of  soldering  for  aluminum  bronze  and 
aluminum,  of  which  we  shall  here  cite  the  most 
important.  According  to  his  directions  also,  the 
metals  must  first  be  tinned  with  tin-aluminum. 


Alumi- 
num. 

Copper. 

Zinc. 

Tin. 

Lead. 

Nickel. 

Type  28  

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17.  To  Delecluse  we  owe  a  very  interesting  in- 
vestigation of  the  processes  for  soldering  aluminum 
and  the  methods  of  preserving  the  elasticity  of  the 
metal  throughout  its  various  manipulations. 

1 8.  Ludovic  Olivers,  by  means  of  a  heated  cast- 
iron  plate,  heats  the  aluminum  to  a  temperature 
of  23o°-25o°C.     He  then  rubs  in  hard  upon  the 
parts  concerned  a  solder  whose  composition  he  does 
not  state,  taking  care  to  see  that  the  solder  is  evenly 
distributed,  by  means  of  a  metal  brush.     The  solder 


1&4  PRODUCTION  OF  ALUMINUM. 

melts,  and  is  properly  deposited  on  the  surfaces. 
In  order  to  remove  the  last  traces  of  oxide,  the 
soldering-places  are  finally  rubbed  off  once  more 
with  care,  the  two  surfaces  are  put  together,  and 
the  soldering  finished  in  the  usual  manner  with  the 
soldering-iron. 

Otto  Nicolai  uses  a  zinc-tin  solder,  or  some  other 
alloy  generally  employed  for  this  purpose,  and 
secures  a  permanent  union  by  covering  the  solder- 
ing-places  with  powdered  cadmium  chloride  or 
cadmium  iodide. 

20.  In  a  very  exhaustive  paper  of  W.  S.  Bates 
before  the  Chicago  meeting  of  the  American  Chemi- 
cal Society  on  March  18,  1898,  he  recommends  the 
alloy : 

Type  37:  70  parts  aluminum,  30  parts  tin, 
which  would  assure  a  very  secure  union,  were  it  not 
for  the  fact  that  in   time  the  alloy  is   subject  to 
molecular  action  which  impairs  its  strength. 

The  alloy 

Type  38:  8 1  parts  aluminum,  19  parts  copper 
melts  sooner  than  the  preceding,  it  is  true;  but  it 
is  not  subject  to  any  molecular  alteration,  and  like- 
wise makes  a  firm  solder. 

Bates  has  obtained  his  best  results  with  a  ternary 
alloy  of  the  composition : 

Type  39:    70  parts  aluminum,   20  parts  tin,    10 
parts  copper  or  silver. 

The  mass-proportions  of  these  metals  may  vary 
between  wide  limits,  but  the  composition  cited  is 


WORKING  OP  ALUMINUM.  18$ 

the  best.  These  alloys  solder  excellently  and  very 
firmly.  Some  of  them  in  the  course  of  a  year  showed 
no  such  alteration  as  is  usually  observed;  others, 
which  had  been  experimentally  placed  in  water  for 
a  month,  showed  themselves  fully  capable  of  resist- 
ance, revealing  no  trace  of  a  galvanic  effect. 

For  a  flux,  in  the  case  of  soft  solder,  which  may 
be  worked  at  a  relatively  low  temperature,  Bates 
uses  zinc  chloride,  stearin,  soap,  sugar,  quick- 
silver chloride,  and  certain  iodides ;  for  hard  solder, 
which  melts  only  at  a  higher  temperature,  borax, 
alkali  fluorides,  lithium  chloride. 

21.  Grant  Hammond  in  San  Francisco  proposes 
for  a  flux  a  mixture  of  iodine,  tin  iodide  and  quick- 
silver iodide,  and  a  hydrocarbon  from  the  vaseline 
series.  F.  A.  Gooch  proposes  a  mixture  of  sodium 
fluoride,  aluminum  fluoride,  and  aluminum-sodium 
chloride;  also  a  composition  of  aluminum  fluor- 
ide, sodium  fluoride,  and  zinc  chloride. 

Grant  Hammond,  finally,  prefers  the  solder: 

Type  40:    100  parts  tin,  20  parts  silver,  10  parts 

zinc,   i  to  6  parts  aluminum, 
to  all  similar  compositions. 

Second  Process:  Autogenous  Soldering.  —  In  the 
case  of  aluminum,  great  difficulties  are  met  with 
in  attempting  to  solder  without  the  aid  of  a  foreign 
metal  or  of  an  alloy. 

i.  Spring  has  shown  that  two  carefully  worked 
pieces  of  aluminum,  if  pressed  together  and  heated 
to  420°  C.,  in  the  course  of  about  eight  hours 


1 86  PRODUCTION  OF  ALUMINUM 

show  signs  of  fusion.  If  one  of  the  pieces  be 
placed  in  a  vise,  the  other  may  be  worked  without 
breaking  off. 

2.  Bourgoin   has  devised  a  number  of  soldering 
processes  which  partly  belong  in  the  group  of  tin- 
soldering  processes,   and  partly  may  be  classified 
in  the  series  of  autogenous  processes.      We   men- 
tion these  for  the  sake  of  completeness. 

3.  We  owe  to  the  firm  of  Heraeus  in  Hanau  a.  M. 
the   following   method.     The   surfaces   of   the   two 
pieces  of  metal  which  it  is   desired  to  unite  are 
thoroughly  cleansed  over  an  area  of  5-10  mm,  and 
are  placed  in  contact  in  this  perfectly  bare  con- 
dition;    the    metal    is    now   heated   by   means    of 
the    soldering-pipe   until  it  is  of  a  perfectly  fixed 
consistency.      When    the   required   temperature    is 
reached,    it   is   thenceforward   kept   constant,    and 
meanwhile    the    two    pieces    pressed    together    are 
hammered   by  a   peculiar  method   until   they  are 
completely  fused  together.     After  the  cooling  down, 
the  union  is  so  firm  that  it  is  loosened  neither  by 
being  suddenly   shaken    nor  by  changes   of   tem- 
perature. 

Electroplating  of  Aluminum. 

In  spite  of  the  great  number  of  experiments  in 
the  electroplating  of  aluminum,  we  have  not,  up 
to  the  present  day,  succeeded  in  obtaining  a  cer- 
tain method  of  coppering,  nickeling,  gilding,  and 
silvering  the  metal. 


WORKING  OF  ALUMINUM.  187 

Coppering.  —  In  an  exhaustive  paper  Margot  re- 
fers to  the  fact  that  the  most  essential  device  for 
securing  a  permanent  deposit  of  copper  on  alumi- 
num consists  in  freeing  the  metal  from  the  coating 
of  oxide  with  which,  of  itself,  it  is  already  covered, 
and  which  continues  to  form  even  in  the  copper 
bath.  With  this  end  in  view,  the  following  pro- 
cess is  suggested: 

1.  The   cleansing   of   the   aluminum   with   alkali 
carbonate,  in  order  to  keep  the  surface  rough  and 
porous. 

2.  The  metal  is  thoroughly  washed  in  running 
water,  and  then  immersed  in  a  warm  solution  of 
about  5  %  hydrochloric  acid ;  it  is  thereupon  cleansed 
with  pure  water. 

3.  The  plates  are  kept  immersed  in  a  moderately 
concentrate,    slightly   acidified   copper- vitriol   solu- 
tion until  an  even  coating  has  formed. 

4.  They  are  thereupon  thoroughly  washed  again, 
until  the  last  traces  of  chlorine  have  been  removed, 
and  finally 

5.  They  are  placed  in  the  galvanic  bath,  where  the 
coppering  takes  place  by  means  of  the  electric  current. 

The  "  Societe  electrometallurgique  franchise"  in 
coppering  aluminum  avails  itself  successfully  of  a 
process  which  is  very  like  that  just  described,  the 
only  difference  being  that,  in  the  coppering  by 
mere  immersion,  the  copper  sulphate  is  replaced  by 
a  slightly  acid  copper-chloride  solution. 

Gilding  and  Silvering. — It  may  be  said  that  since 


1 88  PRODUCTION  OF  ALUMINUM. 

the  first  experiments  in  this  direction  there  is  no 
notable  progress  to  be  recorded.  The  process  of 
Lejcal  gives  very  good  results,  provided  only  thin 
metallic  coatings  are  required.  The  objects  to  be 
silvered  are  heated  to  about  300°  C.  and  rubbed 
with  a  bit  of  wadding  covered  with  tin  chloride; 
in  this  way  we  obtain  a  permanent  coating  of  tin, 
upon  which  the  silver  is  evenly  deposited. 

The  gold  and  silver  baths  of  the  Societe  Vienne 
fr&res  are  likewise  said  to  have  acted  very  well. 
"La  lumiere  electrique"  *  contains  the  following 
information  regarding  them:  The  pieces  which  it  is 
desired  to  solder  are  first  steamed  with  nitro- 
hydrochloric  acid  or  nitric  acid,  and  then  warmed 
to  7o°-8o°.  The  place  of  the  nitric  acid  may  be 
taken  by  other  similarly  acting  reagents;  nitric 
acid  is,  however,  the  most  suitable  and  practical. 
Finally,  after  the  pieces  have  been  cleansed  with 
fine  pumice-stone  in  the  usual  way,  they  are  im- 
mersed in  baths  of  the  following  composition, 
warmed  to  about  2o°-35°  C. 

Silver  bath:  30  parts  silver,  60  parts  cyanide  of 
potassium,  1000  parts  distilled  water. 

Gold  bath:  7  parts  gold,  49  parts  sulphurous 
carbonate  of  soda,  23  parts  cyanide  of  potassium, 
23  parts  sodium  phosphate,  1000  parts  distilled 
water. 

Margot  and  Minet  were  the  first  to  suggest  that 
the  aluminum  be  previously  covered  with  a  thin, 

*"  La  lumiere  electrique,"  July  u,  1891. 


WORKING  OF  ALUMINUM.  189 

firm  coating  of  copper,  according  to  Margot's 
method  mentioned  above,  and  that  the  metal  be 
silvered  or  gilded  only  after  it  has  been  thus  pre- 
pared; in  this  way  aluminum  may  be  nickeled  as 
well,  and,  in  fact,  may  be  plated  with  any  metal 
that  is  capable  of  being  permanently  deposited  on 
copper. 

But  with  the  exercise  of  care  it  should  be  possible, 
in  my  opinion,  to  silver  aluminum  directly,  by  the 
following  method. 

That  the  direct  silvering  of  aluminum  has  hither- 
to scarcely  been  successful  may  be  due  to  the  fact 
that  the  process  was  carried  out  with  neutral  or 
alkaline  baths.  Under  these  conditions  the  metal 
has  a  tendency  to  cover  itself  with  a  film  of  oxide, 
which  is  not  dissolved  again,  and  which  hinders 
the  attachment  of  the  coating  of  silver.  If,  on  the 
other  hand,  the  parts  concerned  are  previously  pre- 
pared and  steamed,  as  Margot  suggests  for  the 
coppering,  and  if  for  the  bath-fluid  a  solution  of 
sodium-silver  double  fluoride  slightly  acidified  with 
hydrofluoric  acid  is  used,  very  good  results  would 
certainly  be  obtained. 

In  view  of  these  considerations,  the  following 
method  recommends  itself.  In  order  to  keep  the 
surfaces  of  the  aluminum  objects  rough  and  porous, 
they  are  first  of  all  cleansed  with  a  diluted,  warm 
solution  of  alkali  carbonate,  and  then  thoroughly 
washed,  immersed  in  a  warm  solution  of  hydro- 
fluoric acid,  and  only  then  suspended  in  the  silver- 


190  PRODUCTION  OF  ALUMINUM, 

fluoride  bath;  any  alumina  that  may  be  formed 
is  immediately  dissolved  by  the  hydrofluoric  acid. 
Under  these  conditions,  when  the  current  is  passed 
through,  a  very  smooth  and  uniform  silver  coating 
is  obtained.  If  the  object  in  question  has  such 
dimensions  as  to  be  steamed  with  difficulty,  i1^ 
is  sufficient  to  connect  it  as  anode  in  the  silver 
bath  for  a  few  seconds,  while  the  fluorine  separating 
off  provides  for  the  steaming.  After  a  short  time 
the  direction  of  the  amount  is  changed,  whereupon 
the  silvering  begins. 

A  general  method  for  obtaining  metal  platings 
of  various  sorts,  according  to  Golting,  consists  in 
immersing  the  aluminum  in  the  metal-salt  solution 
in  question,  and  at  the  same  time  keeping  it  in 
contact  with  a  chosen  metal  of  such  a  kind  that 
the  resulting  combination  forms  a  voltaic  pile  in 
which  the  aluminum  is  the  negative  pole. 

Wagner  has  mentioned  another  process:  Alu- 
minum is  subjected  to  corrosion  in  a  bath  which 
contains  acid  copper  acetate,  iron  oxide,  sulphur 
and  aluminum  chloride ;  it  is  then  rubbed  off  with  a 
brass  brush,  by  means  of  which  a  metal  covering 
is  formed,  which  removes  the  coating  of  grease, 
stops  up  the  pores,  and  levels  the  surface.  Next  it 
is  thoroughly  washed  with  pure  water,  and  finally 
immersed  in  the  electrolytic  cell.  The  method  is 
said  to  give  coatings  capable  of  great  resistance 
and  durable. 

According  to   Lenseigne  and   Leblanc,   the  alu- 


USES   OF  ALUMINUM.  19 1 

minum  objects  to  be  plated  are  steamed  in  dilute 
sodium  lye  or  dilute  potassium  lye  or  in  hydro- 
chloric acid  (1:10),  then  thoroughly  brushed  off 
in  water,  and  finally  heated,  according  to  the  sort 
of  metal  coating  desired,  in  one  of  the  following 
baths: 

Gold  bath :  40  parts  gold  chloride,  40  parts  cyan- 
ide of  potassium,  40  parts  sodium  phosphate, 
2000  parts  distilled  water. 

Silver  bath:     20   parts   silver   nitrate,    40   parts 
cyanide  of  potassium,  40  parts  sodium  phos- 
phate, 1000  parts  distilled  water. 
Copper  bath :    300  parts  cyanide  of  copper,   450 
parts  cyanide  of  potassium,  450  parts  sodium 
phosphate,  8000  parts  distilled  water. 
Nickel  bath :    70  parts  nickel  chloride,    70  parts 
sodium  phosphate,  1000  parts  distilled  water. 
The  temperature  of  these  baths  should  be  6o°- 
70°  C.,   and  should  be  kept  constant  throughout 
the  operation;    for  the  anode  the  metal  may  suit- 
ably be  chosen  whose  salt  is  dissolved  in  the  elec- 
trolyte. 


D.  USES  OF  ALUMINUM. 

Not  merely  as  an  alloy,  but  in  the  pure  state  as 
well,  aluminum  has  been  employed  in  a  great  many 
different  ways  in  commerce  and  in  petty  industries, 
in  large  enterprises,  in  chemistry  and  in  metallurgy. 


IQ2  PRODUCTION  OF  ALUMINUM. 

(a)  Aluminum  in  Commerce   and  Minor  Industry. 

Here  belong  a  large  number  of  articles,  useful 
or  luxurious,  such  as  keys,  visiting-cards,  thimbles, 
brushes,  combs,  letter-cases,  cigar-  and  cigarette- 
cases,  etc.,  for  which  aluminum  is  highly  valued  on 
account  of  its  lightness;  aluminum  also  serves  for 
the  manufacture  of  opera-glasses,  spectacles,  knives, 
watches,  articles  of  adornment;  likewise  for  cook- 
ing and  household  utensils,  cups,  dishes,  chafing- 
dishes,  tea-urns ;  for  military  equipment,  etc.  For 
articles  of  small  or  moderate  dimensions,  where  no 
special  strength  is  required,  this  metal  already 
competes  successfully  with  copper,  nickel,  German 
silver,  and  brass,  since  volume  for  volume  it  is 
cheaper.  But  also 

(b)  In  Greater  Industry 

aluminum  has  found  a  wide  field  of  usefulness. 
First  in  importance,  in  this  connection,  is  cast  alu- 
minum, as  to  the  weight  and  the  use  of  which  the 
last  Paris  Exposition  (1900)  gave  one  a  very  good 
idea.  Maxime  Corbin,  the  discoverer  of  an  alu- 
minium alloy  with  a  strong  resistance,  had  produced 
a  non-separable  mountain  gun-carriage  weighing 
only  78  kg,  while  that  adopted  by  the  French  army 
weighs  285  kg;  the  same  exhibitor  showed  a  model 
for  a  bed-plate  for  an  So-horse-power  dynamo 
machine ;  the  weight  of  this  plate  amounted  to 
185  kg,  while  a  similar  construction  in  steel  would 


USES  OF  ALUMINUM.  v         IQ3 

weigh  380  kg.  Moreover,  Corbin  has  already  sup- 
plied 150  pieces  of  machine-parts  of  this  sort  for 
electric  vehicles. 

Partin  with  his  partinium  obtained  cast  aluminum 
parts  which  had  an  elasticity  of  18-20  kg  per  mm2. 
Single  machine-parts  of  the  sort  at  the  Exposition 
aroused  a  lively  interest  in  professional  circles, 
especially  a  stand  for  a  5o-horse-power  steam-engine, 
with  a  weight  of  only  75  kg.  The  casting  of  this 
large  piece  containing  over  a  cubic  metre  succeeded 
perfectly ;  there  were  no  blow-holes  or  other  defects, 
such  as  often  occur  in  castings. 

The  automobile  and  the  bicycle  have,  of  course, 
opened  up  a  new  field  of  usefulness  for  the  alloys 
of  aluminum,  and  particularly  partinium;  of  this, 
too,  the  last  Exposition  of  1900  afforded  striking 
proof  in  the  exhibition  of  numerous  automobile 
parts,  as  well  as  speed-regulators,  casters,  friction- 
wheels,  and  large  and  small  models  of  every  sort. 

The  visitor's  attention  was  particularly  arrested 
by  an  aluminum  bell,  70  cm  in  height,  50  cm  in 
greatest  width,  and  weighing  about  15  kg;  on 
being  struck  it  gave  forth  a  sound  which  did  not 
differ  from  that  of  a  bronze  bell.  Of  the  other 
objects  exhibited  by  Partin  we  may  mention: 
an  anchor  used  on  several  balloon-trips  by  Messrs. 
Hervieu,  Mallet,  Gilbert,  and  Varicle,  which  was 
found  particularly  serviceable  by  Hervieu  in  one 
of  his  perilous  voyages  in  Russia;  a  pillar  with 
capital,  which  afforded  a  demonstration  of  the  use 


194  PRODUCTION  OF  ALUMINUM. 

of  aluminum  for  ornamental  purposes;  a  chased 
cup,  deceptively  similar  to  old  silver;  a  statuette, 
an  ash-tray,  a  Psyche,  a  beautifully  worked  hand- 
mirror,  a  wash-basin,  a  water-pitcher,  etc. 

We  have  already  emphasized  the  use  of  aluminum 
as  material  for  conducting-wire ;  with  equal  con- 
ductivity it  weighs  and  costs  less  than  copper. 
Aluminum  also  permits  of  being  worked  up  into 
tubes;  such  tubes  are  preferred  for  optical  instru- 
ments. An  attempt  has  also  been  made  to  intro- 
duce aluminum  tubes  in  the  manufacture  of  bicycles ; 
the  frames  were  to  be  made  of  a  light  alloy  to  which 
it  was  designed  to  give  the  greatest  possible  strength 
by  means  of  careful  casting,  remelting,  and  any 
further  treatment  required;  I  believe,  however, 
that  aluminum  will  be  found  to  associate  itself 
with  steel  as  reluctantly  as  do  other  metals,  in  those 
cases  where  lightness  and  an  extraordinary  power 
of  resistance  are  desired. 

Rolled  aluminum  finds  its  chief  application  in 
ship-building  and  for  military  purposes.  The  first 
to  produce  rolled  aluminum  plates  of  large  dimen- 
sions for  ship-construction  was  Charpentier-Page, 
who  also  was  the  first  to  point  out  the  enormous 
advantage  of  aluminum  for  field-equipment  utensils, 
and  who  together  with  Japy  devised  many  and 
various  types  of  these  articles. 

The  countless  mechanical  tests  which  were  made 
by  Charpentier-Page  on  aluminum  and  copper- 
aluminum  alloys  we  have  already  mentioned.  We 


USES   OF  ALUMINUM. 


may  add  here  the  results  of  some  tests  which  con- 
cern themselves  with  an  alloy  having  a  high  power 
of  resistance,  and  it  is  an  alloy  that,  from  a  tech 
nical  point  of  view,  is  most  useful. 

HARD    WIRE. 

2  mm  in  diam.       Density  2.98. 

Electrical  Tests. 

Resistance  per  metre o  .01598/2 

Resistance  per  km  length  and  mm2  cross-section ...    50.1  yQ, 

Copper  wire  of  the  same  dimensions,  at  15°  C 17  .4/2 

Proportion  of  conductivities 34 . 6% 

Mechanical  Tests. 


Test. 

i 

2 

3 

Length  of  test-piece  mm 

Elasticity                                          kg 

I05 
140 

J°5 

105 
I  -i  7    ft  c 

Elasticity   per  mm2  cross-sec- 
tion .             kg 

44   57 

44    2 

A->      go 

Elongation  mm 

•2       C 

?     r 

2     O 

Elongation  % 

•2      T. 

•3      T. 

2     7 

The  usefulness  of  aluminum  for  military  pur- 
poses was  demonstrated  at  the  Exposition  by  a 
most  interesting  object,  namely,  a  movable  bridge 
of  aluminum,  which  the  Sedan  works  had  exhibited 
in  the  "  Palais  des  Armees  de  Terre  et  de  Mer."  It 
is  a  portable  bridge  which  was  constructed  under 
the  direction  of  General  Dumont  and  according 
to  the  plans  of  Commander  Houdaille.  .  Its  span 
is  1 5  m ;  it  consists  of  three  lengthwise  beams  which 
together  weigh  900  kg;  the  weight  of  the  bridge- 
load  is  600  kg,  so  that  the  entire  bridge  weighs. 


196  PRODUCTION  OF  ALUMINUM. 

1 500  kg.  Its  maximum  load  is  officially  given  as  9000 
kg,  i.e.  600  kg  per  metre  of  length.  With  this  load  the 
sag  is  70  mm,  with  the  bridge  unloaded  it  is  22  mm. 

The  bridge  is  strong  enough  to  bear  a  wagon 
with  six  horses,  weighing  together  2300  kg,  and 
forty  men. 

Field-equipment  Utensils.  —  After  the  autumn 
manoeuvres  of  1894  an  explicit  report  was  made 
to  the  French  minister  of  war  regarding  the  experi- 
mental introduction  of  certain  aluminum  utensils 
as  articles  of  equipment.  The  articles  comprising 
the  aluminum  cooking  apparatus,  of  three  different 
sizes,  weigh  540,  285,  and  50  g  respectively.  The 
so-called  small  equipment,  in  which  the  same  ob- 
jects weigh  385,  215,  and  40  g  respectively,  it  is 
true,  gave  less  satisfactory  results  in  the  tests,  for 
while  the  large  equipment  completely  satisfied  all 
requirements  during  the  manoeuvres,  the  small 
equipment  soon  became  unserviceable. 

Since  the  collective  weight  of  the  iron  cooking 
apparatus,  such  as  is  still  used  in  the  French  army, 
is  1385  g,  as  compared  with  875  g  for  the  weight 
of  the  aluminum  utensils,  in  the  latter  case  the 
soldier's  burden  is  lightened  by  no  less  than  510  g. 
Other  countries  besides  France — Germany,  Russia, 
and  Austria  among  them — have  made  thorough 
tests,  and  have  in  part  adopted  aluminum  utensils. 

Skip -construction. — The  first  vessel  in  which  alu- 
minum was  used  in  considerable  quantities  was  the 
"Vendenesse"  of  Count  J.  de  Chabannes  La  Palice, 


USES  OF  ALUMINUM.  IQ7 

which,  built  after  the  plans  of  Victor  Guilloux  of 
Godinot,  sailed  from  St.  Denis  in  December,  1893. 
Throughout  its  voyages  the  behavior  of  the  vessel 
was  carefully  noted  by  Guilloux,  so  that  we  have 
valuable  observations  as  a  result,  of  which  we  shall 
proceed  to  give  the  more  important. 

Three  months  after  sailing  the  vessel  was  sub- 
jected to  a  thorough  inspection  at  Havre,  and  was 
found  to  be  quite  intact  in  its  interior.  On  the 
outside,  in  a  few  places  where  the  paint  had  been 
damaged  in  sliding  down  the  ways  or  during  the 
passage  down  the  Seine,  the  rivet-heads  had  become 
slightly  oxidized;  and  the  bare  spots  showed,  in 
addition  to  a  fairly  uniform  but  otherwise  insig- 
nificant oxidation  due  to  the  formation  of  alumina, 
a  few  more  serious  injuries.  The  vessel  was  re- 
paired and  painted,  and  soon  after  continued  its 
journey.  When  about  two  months  had  elapsed 
it  received  another  overhauling  at  the  dock  at  Hon- 
fleur,  Guilloux  found  the  vessel  on  this  occasion 
in  perfect  condition;  even  in  those  places  where 
mussels  had  become  attached  to  the  hull  and  the 
paint  was  gone,  the  aluminum  had  retained  its 
lustre  unimpaired.  Only  upon  the  deck  were 
noticeable  here  and  there  the  signs  of  incipient 
oxidation;  the  deck,  to  be  sure,  was  not  painted, 
but  merely  covered  with  oilcloth,  most  of  which 
had  worked  loose. 

Even  upon  a  third  professional  inspection  the 
interior  of  the  "  Vendenesse "  was  found  to  be 


198  PRODUCTION  OF  ALUMINUM. 

wholly  undamaged ;  except  that  in  the  places  where 
the  water  had  worked  its  way  in  beneath  the  wooden 
planking  there  was  a  clearly  perceptible  yet  unim- 
portant effect  upon  the  metal.  The  deck,  on  the 
other  hand,  throughout  its  entire  extent  was  covered 
with  a  layer  of  alumina,  fragments  of  oilcloth  and 
iron-lime,  which,  carefully  collected,  dried,  and 
analyzed,  gave  a  total  weight  of  8  kg,  including 
5  kg  of  aluminum.  This,  calculated  for  the  entire 
surface  of  the  deck  (20  sq.  m),  expresses  a  loss  of 
o.i  mm,  which  could  have  been  avoided  by  paint- 
ing, and  which,  moreover,  would  not  result  in  any 
serious  inconvenience  if  the  oxidation  were  but 
equal  in  amount  over  the  entire  surface,  so  that 
the  durability  of  the  metal  parts  concerned  might 
be  previously  determined.  Unfortunately,  this  is 
not  the  case,  for  while  some  of  the  riveted  plates 
of  which  the  deck  consisted  were  equally  affected, 
others  showed  very  irregular  unevennesses  and 
depressions ;  the  plate  farthest  aft  was  most  affected ; 
the  parts  in  the  neighborhood  of  a  (copper)  venti- 
lating device  had  also  suffered  severely. 

The  parts  which  were  most  oxidized  were  filed 
till  the  coating  of  alumina  was  entirely  removed, 
and  were  then  immersed  in  pairs  in  a  solution  of 
sodium  chloride,  in  order  to  measure  the  electro- 
motive force  of  the  chain  eventually  formed.  It 
amounted  to  0.05-0.10  volts,  and  attained  its  high- 
est value  when  the  most  oxidized  plate  was  taken 
as  the  cathode.  It  follows  from  this  that  in  making 


USES  OF  ALUMINUM.  199 

the  deck  plates  not  chemically  identical  were  used, 
so  that  it  was  possible  for  local  currents  to  be 
formed  which  resulted  in  oxidation.  In  ship- 
construction,  therefore,  it  is  a  most  essential  con- 
dition that  only  such  aluminum  shall  be  used  as 
has  become  wholly  homogeneous  by  means  of  a 
series  of  careful  re-meltings. 

How  important  a  condition  this  is  may  be  seen 
from  the  fact  that  the  torpedo-boat  "La  Foudre," 
which  the  French  government  had  built  by  the 
English  firm  of  Yarrow  shortly  after  the  trial  trips 
of  the  "  Vendenesse,"  quickly  went  to  pieces,  since 
sufficient  care  was  not  taken  that  homogeneous 
metal  should  be  employed  exclusively. 

Among  other  aluminum  vessels  we  may  mention: 

The  portable  boats  of  Lefebvre  (built  jointly 
with  Guilloux)  which  during  the  last  few  years 
have  been  despatched  to  African  waters,  and  have 
there  done  good  service.  A  model  was  exhibited 
at  the  World's  Fair  of  1900 :  the  portable  "  Etienne  " 
(10  tons),  with  a  total  weight  of  1050  kg,  built  in 
the  year  1893,  restored  by  Colonel  Marchand  after 
a  three  years'  voyage  on  the  Congo.  On  this  vessel 
Commander  Baratier  explored  the  whole  of  Bakr- 
el-Ghazal,  and  Marchand  made  the  journey  to  Fa- 
choda  (July  10,  1898).  This  expedition  was  accom- 
panied by  the  two  vessels  ' '  Commandant  Besan- 
gon  "  (8  tons,  400  kg  in  weight)  and  "Jules  Davoust," 
both  of  which  were  built  in  the  year  1893. 

The  vessels  "Crampel,"  "Lauziere,"  and  "  Plei- 


200  PRODUCTION   OF  ALUMINUM. 

gneur "  (13  tons)  were  still  in  use  in  1900  on  the 
waters  of  the  Congo,  while  "Grail,"  "  Livrell," 
"Pronci,"  and  "  Jansaric "  (50  tons;  built  1894) 
were  plying  to  and  fro  upon  the  Niger. 

The  materials  for  these  vessels,  aluminum  plates, 
were  furnished  chiefly  by  the  factories  of  Char- 
pentier-Page  and  the  Sedan  Works,  under  the 
direction  of  Dreyfus,  Paris  representative  of  the 
"Societe  electrometallurgique  fran^aise."  Sev- 
eral 'pleasure-yachts  were  also  built  in  Germany 
and  in  Switzerland.  Escher  Wyss  &  Co.  in  Zurich 
exhibited  at  the  World's  Fair  a  vessel  with  a  two- 
horse-power  petroleum  motor,  which  weighed  400 
kg  and  was  able  to  cover  5-6  knots  per  hour; 
also  a  small  boat  for  four  persons,  weighing  but 
48  kg. 

Of  racing-boats  we  may  mention:  the  "Luna" 
of  Mr.  Arons  (5  tons)  and  the  "  Alumin "  of  Mr. 
Huldschinski  (10  tons),  both  in  Berlin.  The  racing 
for  the  "America"  Cup  in  the  year  1895  is  still  fresh 
in  the  minds  of  all,  in  which  the  American  yacht 
"  Defender  "  and  the  English  "  Vigilant  "  took  part. 
The  latter  was  sheathed  with  plates  of  Tobin 
bronze,  the  former  with  plates  of  bronze-aluminum. 

That  aluminum  has  rendered  good  service  in 
aeronautics  as  well,  we  have  already  remarked: 
in  this  connection  it  serves  principally  for  the 
manufacture  of  the  balloon-car;  and  it  has  been 
employed  for  this  purpose  most  advantageously, 
since  this  inner  stiffening  has  made  the  balloon  much 


USES    OF  ALUMINUM.  201 

better  able  to  withstand  storms  and  accidents, 
and  much  more  reliable.  The  Russian  engineer 
Tschernouchouko  has  built  a  balloon  of  this  sort, 
which  with  a  weight  of  4800  kg  was  able  to  lift 
100  men  and  a  ton  of  baggage. 


(c)   Aluminum  in  Chemistry  and  Metallurgy. 

Aluminum  is  much  used  as  a  reducing-agent  in 
melting  cast  iron,  in  refining  steel,  in  the  produc- 
tion of  certain  metals,  in  aluminothermy,  so  called; 
also  in  the  production  of  phosphorus  and  in  photo- 
chemistry. 

The  Production  of  Phosphorus.  —  Accidentally, 
during  his  investigations  as  to  the  possibility  of 
soldering  aluminum,  Professor  Rossel  in  Bern 
observed  that  phosphates  are  reduced  by  aluminum. 
When  Rossel  heated  a  mixture  of  aluminum-foil 
and  phosphoric  substances  (phosphates)  in  a  porce- 
lain crucible,  he  observed  that  little  flames  spurted 
out  at  the  side  of  the  melt.  He  repeated  the 
experiment  in  a  closed  tube,  in  order  to  avoid  the 
oxidation  of  the  vapors  passing  off,  and  could  thus 
easily  demonstrate  the  presence  of  phosphorus  in 
the  product  of  reaction,  with  a  consumption  of  about 
30%  of  the  original  material.  In  order  to  reduce 
all  the  phosphoric  acid  to  phosphorus,  to  the  mix- 
ture of  aluminum  and  phosphates  (or,  better,  meta- 
phosphates)  silica  had  to  be  added. 


262  PRODUCTION  OF  ALUMINUM. 

In  Photochemistry  aluminum  may  be  employed 
in  two  ways.  According  to  the  suggestion  of  the 
French  chemist  Clemmon,  gold  and  silver  from 
photographic  baths  which  can  no  longer  be  used 
are  to  be  precipitated  in  such  a  manner  that  an 
aluminum  plate  may  be  immersed  in  the  solution, 
the  latter  having  been  strongly  acidified  with 
hydrochloric  acid;  gold  is  separated  off  directly, 
with  the  formation  of  abundant  gases;  silver  is 
precipitated  as  a  chloride. 

A  second  theory  originates  with  Professor  Glus- 
maff.  His  idea  is  to  use  aluminum  instead  of 
magnesium  as  a  source  of  light  for  taking  photo- 
graphs in  the  dark;  and  he  gives  the  following 
receipts : 

1.  21.7    parts    powdered    aluminum,    13.8    parts 

sulphide  of  antimony,  64.5  parts  potassium 
chlorate. 
The  combustion  of  this  mixture  lasts  but  fa  second. 

2.  30  parts  powdered  aluminum,  70  parts  potas- 

sium chlorate. 

This  mixture  dies  out  within  -J  second. 

Aluminum  has  still  another  chemical  function,  as 
reducing-agent  in  refining  cast  iron,  steel,  and  other 
metals.  The  formation  of  an  oxide,  which  happens 
during  the  melting  of  many  metals  in  air,  is  pre- 
vented when  aluminum  is  added,  on  account  of  the 
reductive  properties  of  the  latter ;  certain  impurities 
present  in  the  metals  are  likewise  reduced,  so  that  a 
casting  free  from  blow-holes  is  obtained,  which  in 


USES  OF  ALUMINUM.  203 

consequence  of  the  elimination  of  the  oxides  likely 
to  be  enclosed  is  neither  fissured  nor  brittle.  Ac- 
cording to  Langley,  aluminum  is  to  be  added  in  the 
following  quantities,  according  to  the  nature  of  the 
metal  to  be  refined: 

0.016-0.030%  Al  to  Martin  steel  with  0.5%  C. 

0.020-0.050%  Al  to  Bessemer  steel  with  o.5%C. 

0.011-0.025%  Al  to  Bessemer  steel  with  more 
than  0.5%  C. 

The  Aluminium-Industrie-Aktien-Gesellschaft  re- 
fines 

steel          with  0.004-0.025%  aluminum 

soft  steel    "  o.oi  -0.1% 

cast  iron  0.2% 

copper  o.i     -0.25% 

brass  "  o.i     -0.50%          " 

nickel  0.027-0.09% 

Foucau  is  of  the  opinion  that  in  the  metallurgy 
of  iron  it  will  be  possible  to  avoid  entirely  the 
production  of  carboniferous  ferro-silicon,  and  to 
limit  to  a  considerable  extent  the  use  of  ferro- 
manganese,  since  aluminum  is  destined  to  replace 
the  former  altogether,  and  the  latter  in  those  cases 
which  are  not  directly  concerned  with  the  separation 
from  sulphur.  In  the  case  of  nickel-steel,  aluminum 
may  likewise  be  employed  to  advantage,  since  it 
considerably  simplifies  the  casting.  With  other 
metals  as  well  as  iron,  very  pure  and  uniform  cast- 
ings are  obtained  with  the  aid  of  aluminum,  castings 


204  PRODUCTION  OF  ALUMINUM. 

which  satisfactorily  withstand  the  effect  of  cold  of 
of  heat. 

Keep,  engineer  of  the  American  The  Michigan 
Stove  Works  Company,  jointly  with  Mabery  and 
Vorce  has  investigated  very  thoroughly  the  effect  of 
aluminum  upon  molten  iron,  and  has  been  able  to 
demonstrate  that  aluminum  changes  into  graphite 
the  carbon  that  is  in  chemical  union  and  that  which 
is  dissolved,  and  in  some  peculiar  way  hinders 
the  carbon  from  raising  blisters;  on  the  contrary, 
it  brings  about  the  even  distribution  of  the  carbon 
throughout  the  mass  at  the  moment  of  cooling. 

The  effect  of  various  quantities  of  aluminum 
upon  white  cast  iron  in  particular  is  given  in  the 
following  table: 

Adding  o%  aluminum,  white  fracture. 

°-25%  grayish-white  fracture. 

°-5°%      "          lustrous  gray  fracture. 
°-75%      "          graY  fracture. 
1.00%      "  dark  gray  fracture. 

0.25%  aluminum,  according  to  Keep,  is  equivalent 
to  0.62%  silicon,  in  so  far  as  the  nature  of  the 
surfaces  of  fracture  is  concerned. 

The  effect  of  aluminum  on  iron  carbide  has  been 
carefully  investigated  by  T.  W.  Hogg.  He  first 
points  out  that  in  these  carbides  so  many  foreign 
elements  are  contained,  in  such  various  propor- 
tional quantities,  that  it  is  exceedingly  difficult 
to  determine  precisely  the  role  of  each  in  the  dif- 


USES  OF  ALUMINUM.  205 

ferent  modifications  of  the  carboniferous  iron 
exposed  to  the  effect  of  the  aluminum.  The  dif- 
ficulty of  such  an  investigation  is  all  the  greater 
if  we  take  into  account  the  effect  which  certain 
special  conditions,  such  as  the  variations  in  the 
melting-point  and  the  rapidity  with  which  the 
cast  iron  stiffens,  have  been  found  to  produce. 

Another  circumstance  which  materially  affects 
the  readiness  with  which  the  carbon  passes  from 
the  chemically  united  into  the  graphitic  state  is 
the  amount  of  carbon,  in  particular,  contained  in 
the  iron.  In  this  respect  the  iron  may  be  com- 
pared to  some  extent  with  a  more  or  less  saturated 
salt  solution.  T.  W.  Hogg  has  made  numerous 
experiments  in  the  effort  to  throw  some  light  upon 
this  question,  which  has  hitherto  been  but  little 
investigated.  He  found  that  the  addition  of  i% 
of  aluminum  considerably  modified  the  carbon 
which  was  in  chemical  union,  since  it  changed  the 
latter  into  graphite.  With  the  addition  of  more 
aluminum  the  carbon  gives  evidence  of  a  tendency 
to  return  again  to  its  original  condition;  in  the 
presence  of  12%  of  aluminum  it  has  usually  re- 
turned to  that  state. 

In  a  paper  appearing  in  September,  1891,  which 
treats  of  the  use  of  aluminum  in  refining  steel, 
Le  Verrier,  Professor  at  the  "  Conservatoire  des 
Arts  et  des  Metiers,"  comes  to  the  following  con- 
clusions : 

i.  Aluminum  is  an  energetic  reducing-agent,  and 


206  PRODUCTION   OF  ALUMINUM. 

although   it   is   difficult   to   oxidize   it   directly,    it 
reduces  almost  all  metallic  oxides  in  the  heat. 

2.  Aluminum    causes    soft    steel    in    the    molten 
state  to  flow  easily. 

3.  Aluminum  prevents  blistering  better  than  any 
other  addition. 

Aluminum  as  Reducing-agent  in  the  Production 
of  Metals  and  Alloys. — We  have  already  (page  171) 
cited  an  example  for  the  production  of  an  alloy 
(chromium-aluminum)  by  the  reduction  of  the  salt 
concerned  with  aluminum,  according  to  Wohler, 
who  in  fact  was  the  first  to  use  metals  as  reducing- 
agents  in  pyro-chemistry. 

Charles  Combes  has  published  a  very  interesting 
paper  dealing  with  this  subject,  which  he  laid  be- 
fore the  "  Academic  des  Sciences"  on  June  25,  1896. 
He  succeeded  in  producing  the  following  alloys : 

Nickel-aluminum,  with  20%  Nickel. — Aluminum 
is  allowed  to  work  upon  nickel  sulphite  (NiS) ; 
the  reaction  takes  place  with  violent  boiling. 

Manganese-aluminum.  —  Anhydrous  manganese 
chloride  is  introduced  into  molten  aluminum ;  there 
are  formed  aluminum  chloride,  which  quickly 
evaporates,  and  may  be  received  in  a  condenser, 
and  an  alloy  containing  4%  manganese,  with  the 
fracture  crystalline  and  similar  to  specular  cast  iron. ' 

Chromium-aluminum. — Aluminum  and  chromium 
chloride  (with  a  violently  foaming  reaction)  give 
the  alloy  already  discovered  by  Wohler.  With 
7%  of  chromium  it  is  brittle  and  has  a  crystalline 


USES  OF  ALUMINUM.  207 

structure;   with  13%   of  chromium  it  is  perfectly 
crystalline,  and  may  be  powdered  in  mortars. 

Aluminothermy. 

Up  to  this  point  we  have  only  described  such 
processes  for  the  production  of  aluminum  alloys  as 
depend  on  the  reduction  by  means  of  haloids  or 
sulphides.  Besides  these  there  is  a  further  group 
of  methods  which  may  be  classified  under  the  term 
"  Aluminothermy,"  and  which  have  for  their  object 
the  reduction  of  metallic  oxides. 

As  early  as  the  year  1885  the  brothers  Tissier 
attempted  to  reduced  manganese  by  means  of 
aluminum,  without,  however,  arriving  at  any 
result.  Later  they  heated  an  equivalent  of  iron 
oxide  with  three  equivalents  of  aluminum  to  a 
white  glow,  and  thus  obtained  amid  explosive 
phenomena  a  metallic  regulus  with  60.3%  iron  and 
39.7%  aluminum. 

Copper  oxide  also  is  reduced  by  aluminum  at  a 
white  glow;  in  the  case  of  litharge  the  reduction 
takes  place  at  precisely  its  own  melting-point,  and 
so  violently  that  the  melt  may  be  tossed  up  out 
of  the  crucible  so  that  it  raises  the  roof  of  a  small 
Perrot  gas-furnace.  The  same  phenomenon  was 
also  observed  by  Boussingault, .  and  Richards  men- 
lions  it  in  his  work  on  aluminum. 

Ritto  has  reduced  uranium  oxide  by  means  of 
granulated  aluminum,  and  thus  obtained  an  alloy 
with  65%  uranium  and  35%  aluminum.  Moissan, 
among  other  things,  has  succeeded  in  introducing 


208  PRODUCTION   OF  ALUMINUM. 

the  metals  hardest  to  fuse,  such  as  molybdenum, 
tungsten,  titanium,  chromium,  etc.,  into  pig  iron, 
cast  iron,  steel,  and  bronze,  with  the  aid  of  alloys 
which  were  produced  by  means  of  the  direct  reduc- 
tion of  the  oxide  concerned  with  aluminum  or  some 
other  flux.  The  reduction  of  silica  as  well  was 
made  possible  in  this  way.  If  two  molecules  SiO2 
and  four  molecules  Al  are  thoroughly  mixed  and 
carefully  heated,  at  800°  C.  the  reduction  from 
silica  to  silicon  takes  place. — The  author  has  ob- 
tained a  metal  very  rich  in  silicon  by  introducing 
potassium  silicate  into  melted  aluminum. 

Researches  of  Hans  Goldschmidt. — While  all  the 
investigators  hitherto  mentioned  obtained  only  alu- 
minum alloys,  Hans  Goldschmidt  was  the  first  to 
produce  pure  metals  by  means  of  the  reduction  of 
certain  oxides;  he  may,  therefore,  properly  be 
called  the  father  of  aluminothermy.  Many  experi- 
ments before  the  time  of  Goldschmidt  had,  indeed, 
taught  that  the  reduction  of  certain  metallic  salts 
and  metallic  oxides  takes  place  with  extreme  vio- 
lence, sometimes  even  explosively;  there  was  lack- 
ing, however,  any  definite  information  as  to  the 
height  of  temperature  of  the  reaction.  It  was  not 
yet  known  that  the  temperature  of  combustion  of 
aluminum  was  sufficiently  high  to  melt  alumina  and 
even  chromium  without  the  presence  of  a  flux, — 
the  latter  metal,  as  is  known,  being  among  the 
most  refractory ;  up  to  that  time  it  had  been  found 
infusible  even  in  the  electric  arc, 


USES  OF  ALUMINUM.  209 

If  one  compares  the  heat  of  combustion  of  cer- 
tain other  elements,  as  given  in  the  tables  of  Landolt 
and  Bornstein,  with  that  of  aluminum,  as  it  was 
obtained  by  Dr.  Strauss,  physicist  of  the  firm  of 
Friedrich  Krupp  in  Essen,  we  have  the  following 
instructive  figures,  which  we  take  from  a  reference 
of  Goldschmidt's: 


Hydrogen  .  ...................  34000  cal. 

Carbon  ............  ..........  8317  " 

Aluminum  ...................  7140  " 

Magnesium  ...................  6077  " 

Phosphorus  ...................  5964  " 

Sodium  ......................  3293  " 

Calcium  ......  ,  .  .  ,  ............  3283  " 

Sulphur  ......................  2200  " 

Zinc  .........................  1314  " 

Copper  .......................  321  " 

Silver  ........................  27  " 

If  operations  are  carried  on  with  large  quantities, 
as  was  Goldschmidt's  intention,  a  twofold  difficulty 
is  met  with.  In  the  first  place  the  violence  of  the 
reaction  must  be  lessened  as  much  as  possible,  and 
in  the  second  place  a  crucible  material  must  be 
found  which  is  not  affected  by  aluminum  in  the 
molten  state.  The  reaction  must  take  place  in  such 
a  manner  that  the  alumina  as  it  forms  is  deposited 


210  PRODUCTION  OF  ALUMINUM. 

upon  the  inner  surface  of  the  reaction-vessel,  so 
that  the  receptacle  is  protected  in  and  of  itself  from 
further  attack  through  the  formation  of  the  layer 
of  alumina. 

Another  point  was  to  decide  the  question,  theo- 
retically and  practically  of  equal  importance, 
whether  it  was  possible  so  to  conduct  the  reaction 
that  the  combustion  once  begun  should  continue  of 
itself  without  any  further  addition  of  heat;  and 
whether,  indeed,  the  combustion  might  not  take 
place  either  cold,  provided  that  the  mix  is  in  and 
of  itself  able  to  maintain  the  combustion,  or  warm, 
that  is  to  say,  in  such  a  manner  that  the  mix  is  first 
brought  to  a  temperature  favorable  to  the  further 
spontaneous  course  of  the  reaction,  and  is  then  left 
to  itself.  This  temperature,  of  course,  could  only 
have  been  determined  experimentally. 

One  may  easily  imagine  the  technical  difficulties 
which  stood  in  the  way  of  carrying  out  this  alu- 
minothermic  process, — difficulties  which,  indeed, 
could  never  have  been  overcome  if  in  practice  it 
had  proved  necessary  as  a  preliminary  to  heat 
the  mixture  to  the  temperature  of  combustion  by 
external  means. 

The  first  metal  which  Goldschmidt  endeavored 
to  produce  alummotherrmcally  was  chromium. 
After  he  had  ascertained  that  chromium  oxide  may 
be  reduced  by  means  of  aluminum,  he  mixed  both 
substances  thoroughly  in  a  crucible,  and  attempted, 
at  first  with  a  slender  flame,  to  kindle  the  mixture 


USES  OF  ALUMINUM.  211 

locally;  only  after  repeated  unsuccessful  attempts, 
however,  did  he  succeed  in  discovering  the  con- 
ditions under  which  the  mixture  actually  burns 
and  the  reaction,  after  the  point  of  combustion 
has  been  reached,  proceeds  in  such  a  manner  that 
it  may  easily  be  controlled.  A  new  method  of 
thermochemical  investigation  was  revealed  by  these 
pioneer  researches,  and  at  the  same  time  the  founda- 
tions were  laid  for  a  new  branch  of  industry — alu- 
minothermy. 

It  now  became  merely  a  matter  of  developing  the 
method  technically,  especially  with  reference  to 
starting  the  reaction.  It  followed  that  for  this  pur- 
pose a  mixture  of  aluminum  and  such  oxides  or 
superoxides  as  gave  off  their  oxygen  more  readily 
than  chromium  oxide  was  best  adapted.  This 
combustible  material,  with  the  purpose  in  view, 
was  placed  within  the  reaction  material  in  a  small 
hollo  wed-out  space,  and  was  set  on  fire  by  means  of 
a  slender  flame ;  the  reaction  began  within  a  minute 
or  two  thereafter.  In  place  of  the  flame  a  ring  of 
magnesium  at  once  appears,  which  is  brought  to 
combustion  simply  by  a  lighted  match.  The 
inflammatory  mixture  which  Goldschmidt  employs 
at  present,  which  he  calls  "  Zundpatrone, "  has  the 
form  of  a  small  pellet  of  powdered  aluminum  and 
barium  superoxide,  to  which  a  strip  of  magnesium 
is  added.  Upon  the  amount  of  combustible  mate- 
rial added,  the  ease  with  which  the  course  of  the 
reaction  is  regulated  depends. 


212  PRODUCTION   OF  ALUMINUM. 

In  this  way  Goldschmidt  succeeded  in  obtaining 
several  kilograms  of  chromium  at  a  single  opera- 
tion, and,  as  early  as  1894,  he  obtained  at  each 
charge  not  less  than  25  kg  of  this  metal. 

Further  experiments  have  shown  that  a  large 
number  of  metals,  especially  manganese  and  iron, 
behave  like  chromium.  A  part  of  the  aluminum  in 
the  operation  may  be  replaced  by  magnesium  or 
calcium  carbide;  in  the  latter  event  the  reduced 
metals  are  more  or  less  carboniferous. 

Likewise  in  place  of  the  oxides  sulphides  or  other 
metallic  salts,  especially  sulphates,  may  be  used.  A 
mixture  of  pure  iron  oxide  and  aluminum  gives 
wrought  iron  directly. 

Technically,  Goldschmidt's  process  may  be  em- 
ployed in  three  different  ways: 

1.  For  the  production  of  pure  metals. 

2.  "     "  "  "    corundum. 

3.  "  various  thermic  purposes. 

i.  The  Production  of  Pure  Metals. — Experiments 
have  shown  that  even  with  a  very  slight  excess  of 
metallic  oxide  metals  or  alloys  entirely  free  from 
aluminum  may  be  obtained.  This  fact  is  very 
remarkable,  on  the  one  hand  because  aluminum 
possesses  the  property  of  being  alloyed  with  extreme 
ease,  on  the  other  hand  because,  as  we  know,  reduc- 
tion by  means  of  carbon  never  results  in  metals  free 
from  carbon  being  obtained, 


USES  OF  ALUMINUM.  213 

Goldschmidt  produces  at  present  in  his  works 
at  Essen  about  100  kg  of  chromium  at  a  single 
charge;  the  melting-crucibles  must  of  course  be  so 
constructed  that  they  are  able  to  withstand  the 
pressure  of  this  mass.  The  work  of  the  operator 
is  confined  to  introducing  the  mixture  of  chro- 
mium oxide  and  aluminum;  the  production  of  100 
kg  of  chromium,  it  is  stated,  takes  twenty -five 
minutes;  the  metal  obtained  is  entirely  free  from 
carbon. 

The  operation  in  the  case  of  manganese  is  alto- 
gether similar;  manganese,  produced  aluminother- 
mically,  comes  upon  the  market  at  present  in  large 
quantities,  of  an  extraordinary  purity.  Titanium 
also  is  produced  by  the  Goldschmidt  process,  not, 
however,  as  pure  metal — on  account  of  its  high 
melting-point, — but  alloyed  with  iron;  further- 
more, barium  oxide  and  lime  may  be  reduced  with 
aluminum. 

In  order  to  convince  himself  of  the  universal 
applicability  of  his  process,  Goldschmidt  has  also 
attempted  to  reduce  most  of  the  other  metal 
oxides  with  aluminum,  without,  however,  obtaining 
in  all  cases  a  well-defined  reaction.  It  is  interesting 
to  note  that  vanadium  acid  up  to  the  present  time 
has  withstood  this  treatment,  which  in  this  case 
resulted  merely  in  the  lower  stages  of  oxidation, 
and  not  in  the  production  of  pure  metal. 

2.  Production  of  Artificial  Corundum. — The  slag 
occurring  in  the  melting-crucible  simultaneously 


214  PRODUCTION  OF  ALUMINUM. 

with  the  formation  of  metal  is  nothing  else  than 
molten  alumina  or  artificial  corundum,  which,  to 
distinguish  it  from  corundum  otherwise  originated, 
is  called  corubis,  and  whose  simultaneous  produc- 
tion considerably  increases  the  economical  value 
of  the  alumino thermic  process. 

3.  The  Generation  of  High  Temperatures;  Soldering. 
— While  heretofore  it  was  necessary  in  welding 
to  employ,  even  for  the  very  smallest  flange,  a 
charcoal  fire  or  a  water-gas  flame,  the  work  of 
soldering  is  by  Goldschmidt's  process  greatly  sim- 
plified. Let  us  suppose,  for  example,  that  it  is 
desired  to  solder  a  flange  upon  an  iron  tube  an 
inch  in  diameter.  The  solder  is  introduced  be- 
twixt the  parts  by  means  of  borax;  the  flange  is 
enveloped  in  a  paper  covering,  which  should  be 
somewhat  wider  than  the  external  diameter  of 
the  disc,  and  on  top  and  at  the  sides  the  latter  is 
covered  with  a  layer  of  sand ;  whereupon  the  whole 
is  placed  in  a  receptacle  of  sheet  metal  of  the 
proper  shape  and  size.  In  place  of  the  paper  cover- 
ing thin  iron  plate  may  be  used.  The  flange  is 
then  immersed  in  the  heating  mixture,  so  that  the 
parts  to  be  soldered  are  completely  covered;  the 
mixture  is  enkindled,  and  finally  dry  sand  is 
poured  upon  it.  The  effect  of  the  heat  developed 
is  to  melt  the  solder,  and  thus  to  bind  both  the 
iron  parts  firmly  together.  The  slag  formed  during 
the  process  is  not  removed,  of  course,  until  it  is 
completely  cooled. 


USES  OF  ALUMINUM.  215 

The  Goldschmidt  method  is  not  yet  available  in 
all  cases,  nor  have  its  possibilities  been  fully  de- 
veloped; but  already  it  is  realized  that  this  new 
process  is  capable  of  extremely  interesting  and 
manifold  applications. 


APPENDIX. 


SUPPLEMENTARY  NOTES   BY  ADOLPHE 
MINET. 

IN  the  course  of  the  two  or  three  months  following 
the  publication  of  the  German  edition,  several 
criticisms  were  made  which  the  author  desirous 
of  accuracy  and  impartiality  could  not,  in  justice 
to  himself,  pass  over  in  silence. 

These  criticisms,  at  least  the  chief  ones,  appeared 
successively  in  the  Zeitschrift  fur  Elektrochemie, 
over  the  signature  of  M.  Haber;  in  Electrochemical 
Industry;  and  in  The  Electrochemist  and  Metallurgist. 

Since  the  majority  of  these  criticisms  have  con- 
cerned themselves  with  the  same  points,  and  the 
German  criticisms  have  been  the  most  numerous, 
this  additional  chapter  has  been  written  mainly 
with  a  view  to  answering  the  criticisms  of  the 
Zeitschrift  fur  Elektrochemie. 

For  the  sake  of  brevity,  I  will  not  reproduce 
the  positions  of  the  text  under  discussion,  but  I 

will  refer  the  reader  throughout  the  course  of  the 

217 


2l8  APPENDIX. 

controversy  to  the  English  text,  which  is  an  exact 
translation  of  the  German. 

Some  of  the  criticisms  concern  themselves  specifi- 
cally with  the  industrial,  others  with  the  theoretical 
aspects  of  the  question;  we  shall,  therefore,  make 
a  twofold  division  of  our  subject-matter. 

INDUSTRIAL  QUESTIONS. 

i.  Mr.  Haber  informs  the  readers  of  the  Zeit- 
schrift  of  his  disappointment,  in  reading  the  German 
version,  at  not  finding  the  valuable  information 
as  to  the  preparation  of  aluminum  he  had  hoped 
to  find. 

The  electro-metallurgy  of  aluminum  being  a 
comparatively  recent  industry,  and  one  which 
has  been  put  on  a  solid  basis  only  after  considerable 
experiment  and  expenditure  of  time  and  money, 
it  seemed  to  lie  outside  my  province  to  give  the  spe- 
cific details  of  manufacture,  as  Mr.  Haber  would 
have  liked,  and  I  deemed  it  best  to  restrict  myself 
to  questions  of  a  general  nature.  The  right  to  do 
otherwise  belongs  to  the  manufacturers. 

Furthermore,  in  technical  works  one  finds  that 
detailed  information  is  only  given  when  the  processes 
have  been  extant  for  a  number  of  years — in  other 
words,  when  they  have  become  classic.  This  is  not 
the  case  with  .the  electro-metallurgy  of  aluminum, 
the  evolution  of  which  is  as  yet  incomplete. 

The  minute  details  of  manufacture  are  not  likely 


APPENDIX.  219 

to  interest  the  majority  of  readers,  who  expect 
to  find  in  a  monograph  a  history  of  the  question 
and  general  information  as  to  the  manipulation  and 
application  of  the  metal. 

2.  My  critic  acknowledges  the  abundance  of 
material  I  have  collected,  but  he  finds  that  "  par- 
ticularly in  the  latter  portion  of  the  book,  the  ex- 
perimental results  are  presented  in  such  form  as 
to  render  almost  nil  the  advantage  of  such  a  collec- 
tion of  facts,  because  the  text  is  not  supported  by 
references  sufficiently  complete." 

This  last  observation  might  be  of  significance, 
were  it  not  for  the  fact  that  during  seven  years 
(1887-1894)  I  was  occupied  almost  exclusively  in 
the  manufacture,  the  manipulation  and  the  appli- 
cation of  aluminum. 

In  so  far  as  the  author  is  concerned,  the  acquired 
experience  might  be  considered  sufficient,  and  the 
book  satisfactory  and  complete,  without  the  cita- 
tion of  references  for  the  facts  which  were  the  results 
of  the  author's  own  observation  and  experiment. 
I  have,  nevertheless,  cited  a  large  number  of  in- 
vestigators, both  engineering  and  commercial,  who 
have  made  contributions  to  the  aluminum  industry, 
and  no  omissions  have  been  brought  to  my  atten- 
tion; the  investigator  who  desires  to  carry  his  re- 
searches further  should  have  recourse  to  the  works 
of  these  authors. 

3.  Among    the   applications    of   aluminum,    it   is 
said  that  I  have  neglected  to  particularize  two  or 


220  APPENDIX. 

three  which  have  rapidly  developed  during  the  last 
few  years,  such  as:  the  use  of  aluminum  in  lithog- 
raphy to  replace  the  lithographic  stone;  the  Ropeer- 
Edelmann  process  for  the  disargentation  of  lead; 
the  use  of  powdered  aluminum  for  colors  in  printing 
and  painting. 

No  doubt  there  are  many  other  applications 
I  have  omitted  to  mention.  This  is  but  natural: 
the  applications  of  aluminum  are  well-nigh  innumer- 
able, and  now  that  its  selling-price  is  hardly  more 
than  half  a  dollar  per  kg,  and  volume  for  volume, 
taking  into  consideration  its  lightness,  it  is  found  to 
be  cheaper  than  most  of  the  common  metals — 
excepting,  of  course,  iron,  zinc,  and  lead — it  would 
be  very  difficult  to  make  a  complete  list.  Never- 
theless, the  examples  given  by  Mr.  Haber  are  of 
interest,  and  I  am  glad  to  have  been  the  occasion 
of  mentioning  them. 

4.  My  statistics  concerning  the  production  of 
aluminum  are  nowhere  near  the  true  figures.  While 
I  have  given,  for  1900,  a  total  production  of  5,000 
tons,  Mr.  Haber  affirms  that  it  amounts  to  8,000 
tons;  other  writers  say  6,000  or  7,000  tons,  others 
still  maintain  that  the  production  of  8,000  tons  was 
not  attained  until  in  1902. 

This  uncertainty  results  from  the  fact  that  it  is 
generally  very  difficult  to  obtain  exact  information 
from  those  interested,  and  this  information,  like 
that  relative  to  the  production,  gives  no  details 
of  the  secrets  of  manufacture.  Furthermore,  it  is 


APPENDIX.  221 

only  possible  to  get  the  figures  second-hand,  given 
in  round  numbers  or  incidentally. 

An  interesting  fact,  for  example,  is  the  amount 
of  energy  necessary  for  the  production  of  a  kilogram 
of  aluminum.  Admittedly,  this  varies  between 
40  and  50  horse-power-hours;  or,  in  other  words, 
with  two  horse-power-days  of  24  hours,  a  kilogram 
of  aluminum  can  be  produced. 

With  the  total  power  of  all  the  manufacturing 
establishments  combined  (see  page  140),  amounting 
to  61,000  horse-power,  the  entire  daily  output  would 
be  30,500  kgs  or  30.5  tons,  and  the  entire  annual 
production  (360  days)  would  amount  to  11,000  tons. 

For  the  selling-price,  it  is  said  that  my  figures 
are  too  high. 

It  is  admittedly  a  difficult  matter  to  establish 
a  fixed  price  even  in  the  case  of  a  long-established 
industry :  it  varies  with  the  locality  according  to  the 
ingredients  needful  for  the  manufacture,  the  skil- 
fulness  of  administration,  the  continuity  of  labor, 
the  price  of  labor,  the  cost  of  the  -reduction  of  the 
ore,  etc. 

The  aluminum  establishments  are  no  exception 
to  the  rule;  and  it  is  impossible  to  give  the  cost  of 
manufacture  of  the  metal,  except  in  general  terms, 
for  the  very  reason  above  given,  that  the  figures 
vary  according  to  the  place  of  manufacture. 

5.  I  have  been  criticised  for  not  having  devoted 
more  than  a  very  few  pages  to  the  Heroult  and  Hall 
processes,  which  are  the  only  ones  at  present  ap- 


222  APPENDIX. 

plied,  while  I  have  described  at  length  and  with 
complaisance  the  process  I  myself  devised — a 
process  which  now  possesses  an  interest  merely 
historic,  though  my  old  establishment  at  St. 
Michel  continues  to  operate,  with  no  precise  infor- 
mation as  to  the  method  employed. 

After  having  passed  in  review  a  certain  number 
of  experiments  which  gave  me  no  significant  results, 
even  in  the  laboratory,  I  have  said  that  only  the 
processes  of  Heroult,  Hall  and  Minet  have  received 
the  sanction  of  practice  (page  78) ;  and  then  I  pro- 
ceed to  describe  them. 

If  I  have  described  my  own  process  at  some 
length,  this  is  only  because  my  process  gave  me  the 
opportunity  to  study  from  the  scientific  point  of 
view  electrolysis  by  igneous  fusion,  and  to  establish 
the  value  of  a  certain  number  of  constants,  little 
known  or  undetermined  before  my  researches 
(1887-1890). 

I  have  at  the  same  time  established  the  regular 
formula  of  electrolytic  reaction,  that  is  to  say,  the 
relation  between  the  current-elements,  electromotive 
force,  bath-resistance,  and  the  intensity,  and  I 
have  indicated  the  different  factors  that  affect  this 
formula  in  terms  of  the  density  of  the  current  at  the 
positive  electrode  (intensity  per  dc2  of  surface  of  the 
anode).  Operating  on  a  similar  bath  at  different 
temperatures,  I  have  determined  that  the  counter- 
electromotive  force  diminishes  in  proportion  as  the 
temperature  increases. 


APPENDIX.  223 

I  have  established  the  influence  which  the  kind 
of  cathode  has  on  the  quantity  of  metal  deposited 
for  a  given  quantity  of  current  traversing  the  bath. 

Finally,  I  have  given  the  results  of  experiments 
showing  that  the  liquid  electrolyte  which  has  been 
the  subject  of  my  observations  was  a  reversible 
electrolytic  system  (page  100). 

The  bath  studied  by  us  was  a  mixture  of  60 
parts  NaCl  and  40  parts  of  Al2F6,6NaF  (cryolite), 
with  a  mixture  of  A^Os  and  A^Fe  for  alimentary 
substances. 

Then  I  have  observed  that  when  one  operates 
on  baths  of  different  composition,  at  least  those 
with  a  base  of  cryolite,  such  as  the  baths  used  by 
Messrs.  Heroult  and  Hall,  where  this  salt  is  mixed 
with  proportions  more  or  less  large  of  chlorides 
and  alkaline  fluorides  and  aluminum,  one  obtains 
for  the  counter-electromotive  force  values  identical 
with  that  of  my  experimental  bath,  where  the 
electrolytic  reaction  is  the  same  in  every  case; 
and  furthermore  the  current-elements  satisfy  the 
same  regular  formulas,  according  to  the  current- 
density  at  the  positive  electrode. 

In  the  paragraphs  treating  of  the  Heroult  and 
Hall  processes,  it  only  remained  to  make  clear  the 
points  of  difference  between  their  methods  and 
mine.  Not  knowing  the  exact  formula  for  the 
baths  employed  by  these  engineers,  I  could  do  no 
more  than  to  describe  their  apparatus.  This  is 
what  I  have  done. 


224  APPENDIX. 

I  might  have  said  that  besides  the  electrolytic 
system  (comprising  furnace  and  baths)  adopted 
in  the  preparation  (properly  speaking)  of  aluminum, 
there  exist  devices  for  the  preparation  of  electrodes, 
for  instance,  from  the  alimentary  products  A12O3 
and  A^FG,  of  which  I  have  made  no  mention. 
To  do  so  would  have  taken  me  too  far  from  my 
subject,  and  it  was  a  matter  too  subtle  to  handle. 

It  is  interesting,  nevertheless,  to  call  attention 
to  the  recent  experiments  made  by  Mr.  Hall,  with 
the  purpose  of  directly  utilizing  bauxite,  partly 
transformed,  in  the  preparation  of  pure  aluminum. 

I  have  myself  made  researches  similar  to  those  of 
Mr.  Hall,  at  the  St.  Michel  establishment  (1892- 
1894)  and  at  the  laboratory  of  Mr.  Le  Verrier  in 
Paris  (1895-1896);  and  the  results  I  have  obtained 
have  been  the  subject  of  communications  made  at 
about  those  dates.  But  this  new  method  is  at  pres- 
ent being  fully  investigated,  and  to  speak  of  it 
in  detail  without  abundant  technical  information 
would  be  inopportune. 

THE  THEORETICAL  PART. 

From  the  point  of  view  of  pure  theory,  Mr.  Haber 
raises  two  questions:  the  one  of  secondary  import- 
ance is  that  which  I  have  first  treated;  the  other, 
on  the  contrary,  is  a  matter  of  the  greatest  interest, 
which  I  shall  strive  to  elucidate,  so  far  as  the  actual 
state  of  the  art  will  permit. 


APPENDIX.  225 

i.  It  has  been  recognized  for  a  long  time  that 
silicon  has  a  deleterious  effect  on  aluminum,  notably 
on  the  resistance  of  this  metal  to  the  attacks  of 
atmospheric  and  chemical  agents. 

Among  other  things,  I  had  noticed  that  the  plates 
or  ingots  of  aluminum  containing  sufficiently  large 
amounts  of  silicon  were  covered,  at  the  end  of 
a  relatively  short  time,  with  a  layer  of  white  powder, 
rasping  to  the  touch,  and  giving  the  sensation,  when 
pressed  between  the  fingers,  of  small  grains  of  sand; 
I  had  concluded  that  this  powder  was  composed 
of  silica,  without  more  exact,  observation,  and  I 
imagined  that  the  silicious  aluminum  must  be  sub- 
mitted to  an  interior  working  of  which  one  of  the 
effects  was  the  displacement  of  the  silicon,  in  propor- 
tion to  the  oxidation  upon  the  surface  (page  144). 

It  was  a  hypothesis  purely  gratuitous,  and  Mr. 
Haber  professes  his  astonishment  that  I  should 
have  adhered  to  it,  which  amounts,  he  declares, 
to  my  saying  that  in  case  there  is  oxidation  this 
would  operate  rather  to  the  detriment  of  the  alumi- 
num than  to  the  detriment  of  the  silicon. 

In  reality,  the  heat  of  formation  of  the  silica 
SiO2  being  equal  to  45  cal.  is  weaker  than  the 
heat  of  formation  of  iA!2O3,  which  is  65.5  cal. ; 
it  follows  that,  of  the  silicon  and  the  aluminum 
present,  it  is  this  last  element  which  is  the  first 
to  be  oxidized.  This  order  of  oxidation  is  certain, 
as  long  as  the  mixture  of  aluminum  and  silicon  is 
intimate;  but  in  proportion  as  the  aluminum  is 


226  APPENDIX. 

oxidized,  small  grains  of  silicon  are  isolated  from 
the  entire  mass  of  the  metal,  surrounded  as  they 
are  by  aluminum,  and  silicon  in  its  turn  is  oxidized. 

With  this  explanation  it  must  also  be  admitted 
that  the  oxygen  of  the  air,  supposing  that  the  metal 
is  not  absolutely  homogeneous,  attacking  more  act- 
ively certain  parts  of  the  surface,  penetrates  further 
and  further  into  the  interior  of  the  mass,  instead 
of  the  silicon  making  its  way  toward  the  surface. 

Although  this  is  true,  from  these  various  hy- 
potheses it  is  certain  that  the  silicious  aluminum 
in  the  condition  of  plates  somewhat  thin,  or  of  fila- 
ments, rapidly  loses  its  mechanical  properties. 
We  have  seen  cases  where,  at  the  end  of  some  months 
of  exposure  to  the  air,  especially  in  the  neighbor- 
hood of  the  sea,  pieces  formed  of  this  aluminum 
had  become  very  fragile;  some  of  them  crumbled 
into  powder. 

The  same  phenomenon  of  disintegration  operates 
slowly  in  the  case  of  light  alloys  of  copper,  even 
when  exempt  from  silicon. 

We  believe  that  the  light  alloys  of  iron  and  of 
manganese  are  those  which  are  disintegrated  least 
rapidly,  in  contact  with  the  air,  and  even  with 
chemical  agents. 

2.  I  shall  now  mention  the  principal  part  of  the 
criticisms  of  Mr.  Haber — that  which  deals  with 
electrolytic  reactions  and  their  continuity,  by 
a  rational  alimentation  of  the  bath  in  proportion 
to  its  decomposition, 


APPENDIX.  227 

The  bath  especially  experimented  with  by  us, 
and  of  which  the  composition  is  given  above, 
corresponds  to  the  formula  i2NaCl  +  Al2F6,6NaF. 

In  proportion  to  its  decomposition  by  the  current, 
it  is  fed  by  a  mixture  of  alumina  and  fluoride  of 
aluminum:  nAl2O3+Al2F6,  with  this  condition,  that 
A1203  should  be  raised  in  proportion  as  the  tempera- 
ture was  lowered;  this  last  observation  had  not 
yet  been  made  by  me  in  the  accounts  of  my  previous 
studies,  or  at  least  it  had  not  been  presented  in  that 
form. 

Experience  has  shown  us  that  in  the  passage 
of  the  current  events  take  place  as  though,  of  all 
the  compositions  present,  only  Ai20s  disappeared, 
whatever  may  be  the  hypothesis  formulated  as 
to  the  electrolytic  reactions  properly  so-called  and 
the  local  reactions;  that  is  to  say,  the  reactions 
do  not  interfere  with  the  counter-electromotive 
force. 

First  Hypothesis.  —  In  case  one  admits  that  A12O3 
dissolves  in  the  bath  and  sinks,  and  that  it  is,  of 
all  the  electrolytes  present,  the  one  that  is  attacked 
by  the  current  —  this  is  the  hypothesis  put  forward 
by  Heroult  and  Hall  —  the  principal  electrolytic  is 
expressed  by  the  relation 


which  becomes,  when  the  quantity  of  current  set  in 
action  equals  96,540  coulombs  (chemical  equivalent 


228  APPENDIX. 

of  electricity) ,  £A12O3  =  t[A!2  +  O3],  the  atomic  weights 
of  the  elements  which  enter  into  reaction  being  taken 
with  a  single  value  and  expressed  in  grammes. 
The  aluminum  goes  to  the  cathode,  the  oxygen  to 
the  anode. 

The  oxygen  in  the  nascent  state  attacks  the  carbon 
of  the  anode  and  forms  carbon  dioxide  O2+  C  = 
CO2.  In  fact  the  anodes  are  consumed  proportionally 
to  the  amount  of  metal  produced. 

Second  Hypothesis. — The  electrolyte  attacked  by 
the  current  is  the  aluminum  fluoride  A12F6 ;  such  is 
my  hypothesis.  Upon  the  passage  of  the  current 
is  produced  the  reaction 

A12F6=A12  +  F6. 

The  aluminum  goes  to  the  cathode,  the  fluorine 
to  the  anode.  Here  are  two  hypotheses  as  to  the 
role  played  by  the  fluorine. 

(a)  The  fluorine  displaces  the  oxygen  of  A12O3 
by  the  reaction  F6  +  A12O3  =A12F6  +  O3;  the  alumi- 
num fluoride  is  regenerated,  and  the  nascent  oxygen 
burns  the  carbon  of  the  anode,  forming  CO2 :   O2  +  C 

=  CO2. 

(b)  The  fluorine,  in  the  nascent  state,  combines 
with  the  carbon  of  the  anode  to  form  a  tetrafluoride, 
F4  +  C=CF4,    and   it   produces    between   CF4   and 
A12O3,  below  or  suspended  in  the  bath,  a  double 
reaction,   3CF4  +  2A12O3  =  2A12F6  +  3CO2,  which  re- 
generates  the   aluminum    fluoride    and   burns   the 
carbon  of  the  anode. 


APPENDIX.  229 

The  analysis  of  the  phenomena  which  may  take 
place  in  the  various  cases  leads  to  the  same  conclu- 
sions as  observation,  that  is  to  say,  that  whatever 
the  hypothesis  adopted,  the  only  electrolyte  which 
disappears  from  the  bath  is  A12O3,  the  aluminum 
precipitating  itself  at  the  cathode,  the  oxygen 
disengaging  itself  in  the  form  of  carbon  dioxide. 
If,  then,  we  proceed  to  a  rational  alimentation,  that 
is  to  say  if  we  feed  the  bath  with  quantities  of 
A12O3  proportional  to  the  quantities  of  aluminum 
precipitated,  the  proportions  of  A12F6  in  the  bath 
remain  identical  with  themselves. 

And  if  we  add  at  the  same  time  with  the  alumina 
certain  proportions  of  A12F6,  it  is  to  compensate 
for  the  very  small  quantities  remaining  of  this 
fluoride,  caused  by  the  fact  that  in  the  hypothesis 
in  which  it  constitutes  the  principal  electrolyte 
it  loses  small  quantities  of  CF4. 

Even  in  the  hypothesis  where  the  principal 
electrolyte  is  a1umina,  there  is  no  doubt  that 
fluoride  of  aluminum  is  decomposed  at  the  same 
time.  The  heat  of  formation  of  Al2Fe  being  nearly 
that  of  A12O3,  with  the  result  that,  in  every  case, 
the  alumina  of  alimentation  should  contain  some 
proportions  of  aluminum  fluoride.  Here  are  the 
objections  raised  by  Mr.  Haber  to  this  theory. 

"The  electrolyte  recommended  by  Mr.  Minet 
(i2Nad+Al2F6,6NaF)  contains  two  anions,  Gland 
F,  and  two  cations,  Al  and  Na,  all  the  anions  as  well 
as  the  cations  in  considerable  proportions. 


230  APPENDIX. 

"According  to  the  law  of  dynamics,  the  current 
discharges  at  the  electrodes  the  materials  of  which 
the  discharge  requires  the  least  effort ;  hence,  in  the 
present  case:  Cl  at  the  anode;  Al  at  the  cathode. 
In  this  way  the  bath  loses  constantly  A12C16, 
and  it  is  necessary  to  add  to  it  this  salt  to  keep 
constant  the  composition  of  the  bath. 

"M.  Minet  is  a  stranger  to  this  point  of  view. 
He  takes  into  consideration  only  the  salts  present, 
A12F3,  NaCl,  NaF,  without  admitting  of  a  change 
of  ions,  and  then  he  thinks  that  it  is  A12F6  which  is 
first  decomposed,  as  having  the  least  heat  of  forma- 
tion, etc. 

"In  this  case  the  electromotive  force  should  be 
3.05,  if  one  allows  70  calories  for  the  heat  of  forma- 
tion of  JA12F6,  while  experiment  gives,  according 
to  the  temperature,  values  of  e  varying  between 
2.17  and  2.5  volts,  which  are  very  near  that  corre- 
sponding to  JA12C16." 

At  the  time  of  my  researches,  and  when  the  Ger- 
man edition  had  appeared,  the  heat  of  formation 
of  JAl2Fe  had  not  yet  been  determined  by  experi- 
ment. I  had  deduced  the  figure  70,  by  comparison 
between  the  heat  of  formation  of  the  hologenic 
salts  of  aluminum  and  of  potassium.  But  since 
then,  M.  Baud  has  established  experimentally  that 
this  heat  of  formation  is  83.17. 

Furthermore,  in  his  argument  M.  Haber  has  not 
taken  account  of  the  presence  of  alumina ;  but  as 
the  heat  of  formation  of  iA!2O3  is  greater  than  that 


APPENDIX.  231 

of  £A12C16,  this  would  not  alter  his  conclusions 
in  the  least  were  not  his  argument  radically  incorrect, 
as  we  shall  demonstrate. 

Let  us  give  first  the  heats  of  formation  of  the  com- 
pounds present  in  the  bath,  and  of  those  which 
might  form  whether  by  the  exchange  of  ions  or  in 
the  secondary  reactions:  these  last  may  be  either 
electrolytic  or  local. 

Let  us  call  C  the  heat  of  formation  in  the  solid 
state  of  the  chemical  molecule  expressed  in  grammes ; 
Tc  the  heat  of  formation  of  the  electrolytic  molecule, 
that  is  to  say  of  the  chemical  molecule  taken  with 
a  single  value  of  each  one  of  the  ions  which  com- 
pose it;  e  the  electromotive  force  corresponding 
to  Tc.  C  and  Tc  are  expressed  in  great  calories,  e 
is  given  in  function  of  Tc  according  to  Thomson's 
rule :  e  =  TcX 0,0434  volts. 


c 

Tc 

e 

A12C16 

323-70 

iA!2Cl6 

53-95 

2-34 

A12O3 

393- 

iA!203 

65-50 

2.84 

A12F6 

499. 

*A12F6 

83-17 

3-6l 

NaCl 

97.90 

NaCl 

97.90 

4-25 

NaF 

110.80 

NaF 

110.80 

4.81 

CF4 

133.60 

iCF 

33-40 

1-45 

CO2 

97.6 

iCO2 

24.40 

i  .06 

M.  Haber  supposes,  then,  that  in  my  bath  it  is 
the  chlorine  which  should  appear  at  the  anode,  while 
aluminum  is  deposited  at  the  cathode,  and  as  proof 


232  APPENDIX. 

in  support  he  remarks  that  the  counter-electromo- 
tive force  which  results  from  this  reaction  (^  =  2.34) 
is  precisely  equal  to  those  which  I  have  found  ex- 
perimentally:  2.5  volts  at  870°;  2.1  at  1,100°. 

Since  he  cites  in  support  of  his  contention  my 
experimental  results,  I  shall  answer  that  in  the  first 
place  experiment  shows  that  not  the  least  trace 
of  chlorine  is  disengaged,  when  one  electrolyzes  a 
dissolved  mixture  of  cryolite  and  alkaline  chlorides. 
This  is  a  fact  conclusively  proved,  for  we  do  not 
discover  about  the  bath  the  slightest  characteristic 
odor  of  chlorine;  and  if  this  halogen  gave  it  off, 
the  atmosphere  round  about  would  be  absolutely 
unbreatheable. 

I  repeat,  I  have  prepared  from  1887  to  1894 
about  100  tons  of  aluminum,  with  the  bath  I  have 
indicated,  and  I  have  never  noted  in  the  atmosphere 
the  least  trace  of  chlorine. 

We  must  then  admit,  in  the  present  case,  that  the 
laws  of  dynamics  may  be  satisfied,  either  that  the 
sodium  chloride  has  not  suffered  any  dissociation, 
or  that  the  relative  values  of  the  heats  of  formation 
of  the  electrolytes  present  are  inverted;  that  is  to 
say,  that  the  heat  of  formation  of  A^CU,  which  at 
the  ordinary  temperature  is  less  than  the  heats  of 
formation  of  A12F6  and  of  A12O3,  is  greater  at  the 
temperature  of  the  operation;  or  rather,  that  the 
phenomenon  takes  place  according  to  the  indications 
which  we  give  in  the  last  paragraph. 

According  to  the  new  order,  it  will  not  do  to  apply, 
except  with  great  discretion,  the  laws  of  dynamics 


APPENDIX.  233 

to  the  dissolved  electrolytes,  if  one  takes  as  a  base 
the  heats  of  formation  taken  at  15°,  and  then  works 
at  temperatures  of  nearly  i  ,000°. 

It  is  preferable  to  follow  another  method  of 
analysis;  for  example,  instead  of  seeking  to  estab- 
lish, a  priori,  the  counter-electromotive  forces  put  in 
play,  as  functions  of  uncertain  heats  of  formation, 
it  is  a  surer  method  to  calculate  these  counter- 
electromotive  forces  as  functions  of  the  regular 
formula,  and  to  deduce  from  the  values  of  e,  thus 
determined,  the  reactions  corresponding.  It  is 
thus  that  we  shall  proceed.  We  know  that  for  the 
current-densities  (intensity  in  amperes  per  sq.  dm) , 
varying  between  2  and  100  amperes,  the  elements 
of  the  current  satisfy  the  given  regular  formula 
E  =  e-\-pI  (page  94),  in  which  E  is  the  difference 
of  potential  taken  at  the  electrodes ;  p  the  resistance 
of  the  bath;  I  the  intensity  of  the  current. 

This  formula  is  applicable  not  alone  to  the  bath 
that  we  have  more  especially  studied,  but  to  every 
bath  containing  cryolite,  even  when  one  changes 
the  proportions  of  the  composition;  it  is  verified, 
whether  in  the  case  of  the  Heroult  bath  constituted 
almost  solely  of  cryolite  and  alumina,  or  in  the  case 
of  Hall's  baths,  in  which  the  cryolite  is  mixed  with 
variable  proportions  of  alkaline  chlorides  and  flu- 
orides and  alumina. 

In  a  word,  in  these  different  baths,  it  is  aluminum 
fluoride,  one  of  the  constituent  parts  of  the  cryolite, 
or  alumina  which  determines  the  counter-electro- 
motive force,  with  all  other  secondary  reactions. 


234  APPENDIX. 

Let  us  now  glance  at  all  the  reactions  which  may 
take  place:  principal  reaction,  secondary  electro- 
lytic reactions,  or  purely  local,  according  as  we 
admit  for  the  electrolytic  principle  A12F6  or  A12O3. 

Value  of  e  deduced  from  the  regular  formula.— 
In  the  bath  which  has  been  the  basis  of  our  study 
the  counter-electromotive  force  deduced  from  [E 
=  e-\-pI}  varies  with  the  temperature  from  2.5 
volts  (temp  .870°)  to  2.17  volts  (temp.  1,100°).  We 
shall  investigate  now  the  reactions  which  correspond 
best  to  these  values  of  e. 

The  principal  electrolyte  is  A12O3. —  (a)  The  sec- 
ondary reaction  is  local.  The  electrolytic  reaction 
is  reduced  to  the  decomposition  of  A12O3  =  A12  +  O3; 
and  for  a  single  valence  JA12O3  =^[A12  +  O3]  Tc  = 
65.5  great  calories. 

ei  =  7^X0.0434  =  65.5  Xo. 0434  =  2. 84  volts,  a  value 
higher  than  that  which  gives  the  direct  measure 
even  for  the  lowest  temperature  870°,  where  e  =  2.50 
volts. 

It  must,  then,  be  admitted,  if  the  case  under 
discussion  is  indeed  a  real  one,  that  we  have  taken 
for  Tc  a  value  too  great;  in  other  words  that  the 
heat  of  formation  of  A12O3  diminishes  in  proportion 
as  the  temperature  is  increased.  In  fact,  experi- 
ence goes  to  show  that  the  electromotive  force, 
of  which  the  value  is  proportional  to  the  heat  of 
formation  of  the  electrolyte,  rises  from  2.50  volts 
at  870°,  to  2.17  volts  at  1,100°. 

(b)    1  he    secondary    reaction    is    electrolytic.      It 


APPENDIX.  235 

should,  then,  re-enter  into  the  calculation  of  the 
counter-electromotive  force. 

In  the  particular  case,  this  secondary  reaction 
is  nothing  but  the  oxidation  of  the  carbon  of  the 
anode  by  the  oxygen  which  originated  at  that  anode 
in  case  (a). 

i(O2  +  C)=iCO2,  Tc  =  24.4,  £2  =  1.06.  This  reac- 
tion being  exothermic,  e2  is  a  sub  tractive  term. 
For  the  values  of  the  counter-electromotive  force 
desired,  it  amounts  to 

£  =  £i  — £2  =  2.84— i. 06  =  1.78  volt, 

a  value  much  less  than  that  which  gives  the  direct 
measure. 

The  principal  electrolyte  is  A12F6. — We  follow  the 
same  method  of  analysis  as  in  the  preceding  hy- 
pothesis. 

(a)  The  secondary  reactions  are  local. — The  elec- 
trolytic reaction  is  reduced  to  JAl2F6=i[Al2  +  F6], 
^  =  83.17,  £1=3.61  volts. 

A  value  much  higher  than  that  of  the  direct 
measure,  but  at  the  same  time  with  this  principal 
reaction  we  know  that  there  result  from  it  second- 
ary reactions  which  have  the  effect  of  fixing  the 
fluorine  while  regenerating  JA12F16,  and  of  burning 
the  carbon  of  the  anode.  They  may  be  produced 
in  two  different  ways. 

(6)   The  secondary  reactions  are  electrolytic. 

(i)  First  type  of  secondary  reactions.  The  fluo- 
rine which  orignates  at  the  anode  there  meets 


236  APPENDIX. 

with  alumina,  in  suspension  or  dissolved  in  the 
bath,  it  attacks  this  alumina  ;  A12F6  is  regenerated, 
and  the  oxygen  resulting  from  the  decomposition 
of  A12O3  burns  the  carbon  of  the  anode.  So  there 
result  two  secondary  reactions,  each  of  which,  if  they 
are  electrolytic,  furnishes  a  sub  tractive  term  for 
the  calculation  of  e. 


(i)  i 

7^  =  83.17-65.5  =  17.67,  ^=0.77, 
e?  =ei  —  e2  =  3.61  —0.77  =2.84. 

Same  value  of  e  as  for  the  case  where  A12O3  is 
the  principal  electrolyte,  without  secondary  electro- 
lytic reaction.. 


(2)  i 

e=ei  —  e2  —  £3  =  3.61—  0.77  —  i.  06  =  1.78. 

Again  the  same  value  as  when  alumina  is  the 
principal  electrolyte,  if  one  admits  that  the  oxida- 
tion of  the  carbon  of  the  anode  is  an  electrolytic 
reaction. 

(2)  Second  type  of  secondary  reactions. 

(a)  The  fluorine  in  the  nascent  state  forms 
with  the  carbon  of  the  anode  a  tetrafluoride  (exo- 
thermic reaction). 


33-40, 


APPENDIX.  237 

The  term  £2  being  sub  tractive,  for  the  value  of 
the  counter-electromotive  force  it  amounts  to 

£'  =  ^  —  02  =  3.61  —  1.45  =2.16. 

Value  very  nearly  that  of  the  direct  measure. 
(b)  The    tetrafluorine    attacks    the  aluminum; 
A12F6  is  regenerated. 


6~l  =104  calories. 

(3X133.6)       (2X393)          _3X97.  6          (2X499)  J 

This    reaction    is  produced  with  a  releasing    of 
104  calories,  which,  taken  at  a  single  valence,   is 

Tc=—  —  ^  =  8.67  calories,  £3=0.376  volt.     The  term 
2X0 

^3  is  subtractive. 


We  return  to  the  case  where  A12O3  is  the  princi- 
pal electrolyte,  with  a  secondary  electrolytic  reac- 
tion. 

To  summarize:  Of  all  the  hypotheses  which  we 
have  just  passed  in  review  that  which  appears  to 
agree  best  with  the  direct  measurement  is  the 
example  (2)  (a)  for  which  the  principal  electrolyte 
is  A12F6,  with  one  secondary  reaction:  an  electro- 
lytic reaction  constituted  by  the  formation  of  a 
tetrafluoride  by  the  fluorine  in  'the  nascent  state, 
and  the  carbon  of  the  anode  ;  the  tetrafluoride  of 


238  APPENDIX. 

carbon  is  released  or  produces  a  local  reaction  con- 
sisting of  the  double  decomposition  between  the 
tetrafluoride  liberated  and  A12O3. 

Whether  there'  be  truth  or  not  in  these  hypotheses, 
one  fact  is  undeniable,  that  when  one  electrolyzes 
a  mixture  of  cryolite  and  sodium  chloride  with 
alumina  in  suspension  or  dissolved  in  the  bath,  the 
electrolytic  reactions  are  explained  by  a  disappear- 
ance of  alumina,  A12O3. 

Let  us  examine,  finally,  the  hypothesis  of  the 
ion  of  chloride  and  of  its  discharge  with  the  method 
employed  above  in  the  study  of  the  electrolyte  of 
A12F6  and  A12O3. 

The  principal  electrolyte  is  A12C13.  —  At  the  tem- 
perature of  the  electrolysis,  A12C16  could  not  exist 
in  the  bath,  in  so  far  as  definitely  compounded, 
but  we  may  express  the  discharge  of  the  ions  Cle 
and  A12  proceeded  from  a  decomposition  of  Al2Cle. 


This  reaction  could  not  be  isolated,  since  we  do 
not  find  any  disengaging  of  chlorine.  So  we  must 
admit  that  this  halogen  is  newly  determined  by  a 
secondary  reaction,  for  example  the  effect  upon 
A12O3  of  Cl  in  the  presence  of  the  carbon  of  the  anode 
with  the  regeneration  of  A12C16. 


2C16  +  2A12O3  +  3C  =  2  A12 


APPENDIX.  239 

This  double  reaction  produces  a  disengaging  of 
heat,  for  the  values  of  7^  =  12.85,  e2=o.$6,  from 
which  0  =  01  —  02  =  2.36— 0.56  =  1.78  volt. 

The  electrolytic  reactions  are  explained  once  more 
by  a  disappearance  of  Al20s,  a  precipitation  of  Al 
at  the  cathode,  and  a  releasing  of  CO2  at  the  anode. 

In  all  the  cases  studied,  the  composition  of  the 
bath  is  kept  constant  by  a  rational  alimentation 
of  aluminum. 

Note  that  the  hypothesis  of  the  discharge  of  the 
ions  Cl  and  Al  at  the  electrodes — if  one  supposes 
that  the  secondary  reaction  is  purely  local — gives  an 
electromotive  force  2.34,  very  nearly  the  value  found 
experimentally.  This  would  be,  then,  a  confirma- 
tion of  a  part  of  the  argument  of  M.  Haber,  for  if 
the  phenomenon  takes  place  thus,  experience  shows 
clearly  that  the  bath  does  not  become  poor  in  A12C16, 
as  this  physicist  maintains,  but  in  A^Os  solely. 


ALUMINUM  IN  THE  UNITED  STATES. 

SUPPLEMENTARY  NOTE  BY  THE  TRANSLATOR. 

IT  was  a  fortunate  thing  for  the  laurels  of  Ameri- 
can metallurgical  engineering  development  that  the 
stalwart  citizen  of  the  Western  Reserve,  Edwin 
Cowles,  then  sixty-three  years  of  age,  leader  of 
Republican  movements,  builder-up  of  the  Cleveland 
Leader,  and  his  two  likely  sons,  Alfred  and  Eugene 
H.  Cowles,  should  in  1883  have  purchased  a  New 
Mexican  mine  on  the  Pecos  River  whose  output 
consisted  of  extremely  refractory  zinc  ores.  Both 
of  the  sons  were  ingenious  and  resourceful.  Eugene 
added  to  a  practical  knowledge  of  the  difficulties 
of  making  solid-steel  castings  the  training  of  a 
writer  on  his  father's  paper  and  the  executive 
experience  of  the  management  of  an  electric  light- 
ing plant  at  a  time  when  difficulties  to  be  overcome 
were  those  of  ignorance  on  the  part  of  a  public  and 
uncertainty  as  to  the  engineering  results  in  the 
output  of  power  and  lighting  plants.  Alfred  had 
followed  more  closely  the  lines  of  study  and  experi- 
mental research.  He  attained  distinction  in  his 
university  life  at  Cornell.  His  mind  was  constantly 
active  and  with  a  strong  tendency  to  at  once  submit 

to  experiment  the  ideas  which  its  fertility  suggested. 

241 


242          ALUMINUM   IN   THE   UNITED  STATES 

In  this  father  and  sons  was  present  that  com- 
bination of  social  and  business  prominence,  mental 
force,  and  courage  of  conviction  necessary  to 
overcome  that  inertia  which  had  up  to  this  time 
relegated  the  possibilities  of  aluminum  to  a  use 
supposedly  remote  in  its  development. 

The  testimony  of  these  gentlemen  in  the  long- 
continued  patent  litigation  forms  the  most  im- 
portant source  of  history  in  this  connection.  A 
sketch  in  the  note-book  of  Mr.  Eugene  H.  Cowles 
dated  June,  1883,  and  bearing  the  title  "Proposed 
Electric  Furnace  for  working  Pecos  Ores,"  contains 
the  essentials  of  the  later  patented  forms  for  the 
smelting  of  aluminum  alloys.  The  mass  of  mixed 
ores  for  reduction  by  incandescent  heat,  the  posing 
inclined  carbon  terminals,  the  vents  at  the  tops  of 
the  furnace,  and  the  tap-hole  for  withdrawing  the 
molten  charge,  are  all  present. 

The  Pecos  River  had  a  fall  of  75  feet  to  the  mile. 
The  absence  of  fuel  made  the  application  of  electrical 
heat  a  thing  to  be  considered.  At  that  time  the 
alternating  current  was  in  a  struggling  infancy. 
The  art  of  building  dynamos  which  should  possess 
enormous  amperage  output  had  not  been  developed. 
When,  therefore,  in  1886  the  Brush  Company  of 
Cleveland,  acting  under  the  enthusiastic  inspiration 
of  the  Cowles  Brothers'  proximity,  built  the  largest 
direct -current  generator  which  the  world  had  seen, 
and  which  produced  thirty -four  hundred  amperes 
at  sixty-eight  volts,  it  was  called,  for  distinction, 
"The  Colossus."  The  output  of  this  machine  was 
consequently  about  230  kw. — a  small  beginning 


ALUMINUM  IN    THE    UNITED   STATES.  243 

as  compared  with  13,000  kw.,  the  estimated  energy 
used  in  the  American  production  of  aluminum  for 
current  American  manufacture. 

The  transition  from  the  application  of  the  electri- 
cal furnace  for  the  smelting  of  refractory  zinc  ores 
to  the  production  of  the  silver  made  from  clay  and 
the  copies  of  gold  known  as  aluminum  bronze  was 
immediate.  Aluminum  in  its  pure  state  had  been 
the  dream  of  chemists.  It  was  so  rare  that  service 
trials  were  practically  unknown.  If  it  could  be 
obtained,  navigation  would  be  immensely  profited, 
for  ships  would  be  light  and  tonnage  vastly  in- 
creased. Railway  trains  would  be  imperishable 
and  track  wearage  reduced  to  a  minimum.  Aerial 
navigation  would  be  expedited.  Military  accoutre- 
ments, fixed  ammunition,  and  guns  would  be 
lightened.  Innumerable  uses  would  spring  up  for 
this  wonderful  metal  which  was  popularly  described 
as  being  as  strong  as  steel  and  but  little  heavier 
than  wood.  The  presence  of  its  ore  in  the  earth's 
crust  in  large  excess  even  of  that  of  iron  itself  would 
furnish  inexhaustible  sources  for  the  new  Aluminum 
Age.  Practical  metallurgists  were  silent  as  to  the 
actual  use  of  aluminum,  for  it  was  not  in  their 
experience.  It  is  no  wonder,  therefore,  that  the 
scheme  of  "  harnessing  Niagara"  should  have 
appealed  vividly  to  the  Cowles  family  and  their 
associated  friends.  The  Pecos  River  had  enabled 
them  to  consider  the  use  of  water-power  as  a  neces- 
sity. The  slightest  calculation  showed  that  the 
units  of  heat  necessary  for  metallurgical  operations 
with  aluminum  ores  required  enormous  power. 


244          ALUMINUM  IN    THE   UNITED   STATES. 

The  proximity  of  Cleveland,  with  the  Brush  works, 
where  machines  could  be  built,  to  the  then  existing 
tail-race  of  the  Niagara  overflow  at  Lockport, 
New  York,  suggested  a  combination  of  agencies 
already  established  which  would  most  quickly  lead 
to  electrical  smelting  on  the  large  scale  necessary. 
We  now  know  that  aluminum  has  most  serious 
drawbacks  to  the  uses  predicted  for  it  by  its  early 
sanguine  exploiters.  No  one  at  that  time  could 
have  foreseen  that  its  largest  use  would  be  as  a 
reagent  in  the  manufacture  of  steel,  and  that  only 
in  combination  with  other  metals  or  even  with  such 
apparently  unrelated  substances  as  phosphorus 
does  it  get  structural  solidity  and  machining  value. 
It  is  yet  to  be  seen  what  the  surprising  development 
of  aluminum  in  aluminothermics  will  be,  but  one 
thing  is  evident,  that  the  freely  disseminated 
literature  issued  by  the  Cowles  Company  in  its 
early  history,  while  it  helped  the  greatest  single 
advance  which  metallurgy  has  made,  was  based 
upon  a  largely  erroneous  view  as  to  the  true  appli- 
cation of  its  results.  The  Cowleses  were  not  the 
people  who  hid  lights  under  bushels.  The  success 
of  the  Cowles  furnaces  at  Lockport  was  at  once 
followed  by  the  description  of  their  results  in  the 
prominent  engineering  journals  of  Europe,  and 
with  characteristic  energy  the  establishment  of 
plants  with  adequate  financial  backing  in  England. 
Most  important  was  the  world -wide  attention  drawn 
to  the  possibilities  of  electric  smelting,  and  the 
establishment  of  the  very  many  works  M.  Minet 
has  outlined  in  this  volume. 


ALUMINUM   IN    THE    UNITED   STATES.  245 

By  far  the  most  important  of  these  outgrowing 
developments  in  the  aluminum  industry,  so  far  as 
America  is  concerned,  was  that  arising  from  the 
work  of  Charles  M.  Hall  of  Oberlin,  Ohio,  who  was 
an  attache  of  the  Cowles  Lockport  works  in  the 
early  years  of  its  history.  The  Cowles  process 
had  failed  to  produce  pure  aluminum  unalloyed 
with  other  metals,  as  a  practical  outcome  from  the 
Cowles  furnaces.  Hall,  after  leaving  the  Cowles 
works,  embodied  a  practical  method  for  the  pro- 
duction of  pure  aluminum  by  electrolysis  in  five 
patents  issued  in  1889.  These  patents  describe 
the  electrolysis  of  alumina  while  held  in  solution 
in  a  molten  bath  of  cryolite  to  which  various  other 
ingredients  have  been  added.  Very  much  has 
been  written  as  to  the  actual  reaction  taking  place 
in  the  Hall  process.  Dr.  Ahrens  *  sums  up  the 
reaction  when  he  describes  the  Deville  work  in  1859 
in  the  following  words  which  I  have  translated: 
"  Deville  thereupon  arrived  at  the  conception  to 
investigate  it  [i.e.,  the  preparation  of  Al  by  elec- 
trolysis] with  other  compounds;  in  a  short  paper 
of  the  year  1859  he  described  a  process  which  rested 
upon  the  principle  of  decomposing  molten  cryolite 
by  the  electric  current,  and  regenerating  the  cryo- 
lite by  the  use  of  anodes  containing  A12O3. 

"Doubtless  Deville  was,  in  this,  reverting  to  an 
analogy  with  the  chemical  preparation  of  Al;  just 
as  by  the  effect  of  Cl  upon  a  mixture  of  A12O3  and 


*  Handbuch  der  Elektrochemie,  von  Dr.  Felix  B.  Ahrens,  Stutt- 
gart, 1903  [ad  Edition],  p.  505. 


246  ALUMINUM  IN    THE   UNITED   STATES. 

carbon,  A1C13  and  CO  are  generated,  so  should  the 
Fl  set  free  by  the  electrolysis  of  cryolite  act  upon 
the  mixture  of  A12O3  and  carbon  of  the  anode,  and 
in  this  way  regenerate  the  A1F3,  which  is  used  by 
the  electrolysis. 

"The  process  of  Deville  failed,  first,  because 
Deville  conducted  from  outside  the  heat  necessary 
for  the  melting  of  the  cryolite,  which  the  decom- 
position-vessels could  not  stand;  then,  however, 
it  failed  at  the  easily  crumbling  carbon — A12O3 
anodes. " 

It  will  thus  be  seen  that  the  essential  point  of  the 
solution  of  alumina  in  molten  cryolite  was  practically 
tried  by  Deville,  and  that  he  himself  offered  the 
explanation  that  it  was  the  cryolite  itself  which  was 
electrolyzed,  while  the  alumina  regenerated  the 
cryolite  instead  of  being  itself  electrolyzed.  This 
distinction  has  an  .important  bearing  upon  the 
patent  situation  when  the  question  of  external 
heating  is  involved.  The  electrolysis  of  alumina 
in  solution  would  require  not  more  than  one-half  the 
voltage  given  as  the  voltage  necessary  in  the  prac- 
tical operation  of  the  Hall  patents  mentioned.  If 
the  required  -voltage  for  the  electrolysis  of  alumina 
only  were  allowed,  in  the  writer's  opinion  it  would 
be  impossible  to  have  operated  the  Hall  processes, 
even  though  abundant  external  heat  was  supplied 
from  non-electrical  sources. 

The  Hall  process  under  the  excellent  manage- 
ment of  the  Pittsburg  Reduction  Company  has 
steadily  developed  until  now  good  judges  base 
the  annual  output  in  America  alone  at  about 


ALUMINUM   IN   THE   UNITED  STATES.          247 

15,000,000  Ibs.  of  pure  aluminum  annually.*  This 
company,  by  wisely  refraining  from  charging  un- 
reasonable prices  by  virtue  of  its  monopoly,  has 
made  it  possible  to  use  aluminum  as  a  staple  at 
a  fixed  price:  a  condition  which  is  primary  to 
extended  uses  in  metallurgical  engineering.  Al- 
though protected  by  a  duty  and  thus  presenting 
one  of  those  unexpected  conditions  under  our  tariff 
by  which  competition  is  completely  suppressed, 
the  cost  to  the  user  has  always  been  just.  For 
some  years  there  existed  a  continuous  litigation 
between  the  Pittsburg  Reduction  Company  and 
the  Cowles  Company,  which  latter  was  enjoined 
from  utilizing  what  seemed  to  them  to  be  a  natu- 
ral development  of  their  process.  Recently  f  the 
Cowles  Company  have  received  at  least  something 
of  poetic  justice,  for  it  has  been  decided  by  the 
courts  that  the  Hall  processes,  having  always  been 
operated  under  the  influence  of  heat  generated  by 
the  current  which  is  used  also  for  the  electrolysis, 
are  subject  to  a  patent  controlled  by  the  Cowles 
Company  issued  to  Charles  S.  Bradley,  in  which 
the  combination  of  the  electrolyzing  and  internal 
heating  current  is  protected.  Mr.  Alfred  H.  Cowles 
survives  his  father  and  brother,  and  alone  witnesses 
this  somewhat  tardy  justice.  Meanwhile  our 
knowledge  of  the  metallurgy  of  aluminum  has 
received  accessions  which  make  more  possible  the 
realization  of  the  predictions  of  twenty  years  ago. 

*See   a   description   of  the    Niagara   Falls   plant,   by  J.  W. 
Richards,  Electrochemist  and  Metallurgist,  Oct.,  1902,  p.  49. 
f  October,  1903. 


248          ALUMINUM  IN    THE   UNITED  STATES. 

For  foundry  purposes  it  is  taking  its  place  with 
other  white  metals  and  is  seldom  used  alone.  Its 
alloys  with  metals  of  its  own  class,  such  as  magne- 
sium and  zinc,  are  rapidly  attaining  commercial 
importance  where  lightness  is  the  desideratum. 
With  steel  a  newly  discovered  but  highly  significant 
use  has  been  found  affecting  the  magnetic  proper- 
ties concerned  in  dynamo  and  transformer  con- 
struction. 

With  reference  to  copper  and  brass  and  the  finest 
of  all  copper  alloys,  the  aluminum  bronzes  or 
aluminides  of  copper,  obstructions  of  an  unexpected 
nature  have  been  met.  The  specific  heat  of  alu- 
minum, its  latent  heat  of  fusion,*  and  the  avidity 
with  which  it  seizes  upon  iron  and  silicon  as  im- 
purities when  in  a  state  of  fusion,  have  been  occult 
reasons  operating  against  its  manufacture  in  works 
regularly  devoted  to  brass  and  copper.  So  strongly 
entrenched  are  the  ideas  of  the  brass  and  copper 
melters  regarding  the  behavior  of  any  white  metal 
like  aluminum — ideas  borrowed  from  the  behavior 
of  tin  and  zinc  at  melting  temperatures — that  it 
is  all  but  impossible  to  secure  technically  proper 
treatment  for  the  copper  alloys  of  aluminum.  This 
has  led  to  the  inaccurate  naming  of  trade  materials, 
so  that  it  is  now  not  possible  to  know  from  a  simple 
announcement  in  trade  circulars  whether  a  metal 
designated  as  aluminum  bronze  may  not  contain 
zinc,  tin,  or  even  lead  as  well. 

*  Total  number  of  calories  to  melt  €11=162,  Al  =258.3^6  = 
370,  Au=  50.9,  Ag=89-2,  Pb=  15.6,  Zinc  =  6 7. 8.  (From  Electro- 
chemical and  Metallurgical  Industry,  July,  1905,  J.  W.  Richards.) 


ALUMINUM  IN  THE   UNITED  STATES.          249 

There  is  a  tendency  on  the  part  of  metallurgical 
engineers  to  depart  from  the  production  of  alumi- 
num from  its  oxide.  Bauxite  is  limited  in  amount, 
and  for  any  large  production  the  question  of  freight 
charges  or  propinquity  of  water-power  or  the  two 
together  is  a  controlling  factor.  The  presence  of 
large  bodies  of  excellent  clays  and  the  very  high 
efficiency  recently  attained  in  the  modern  types  of 
large-unit  gas-engines  promise  in  the  not  too  distant 
future  to  completely  change  the  sources  and  methods 
of  production  of  metallic  aluminum. 

Much  has  been  written  upon  the  uses  of  aluminum 
for  electrical  conductors.  It  is  generally  assumed 
that  for  equal  cross-sections  we  can  now  reach  a 
two-thirds  conductivity  of  copper.  It  is  not  im- 
probable that  this  may  be  largely  increased,  since 
so  far  we  have  not  been  able  to  manufacture  alu- 
minum of  a  corresponding  purity  with  copper.  If 
the  same  kind  and  amount  of  impurity  were  intro- 
duced into  our  present  good  copper  as  now  exists 
in  our  best  aluminum,  the  conductivity  of  the  copper 
would  surely  be  lowered  more  than  ten  and  possibly 
more  than  fifteen  per  cent.  In  Appendix  A  the 
conductivity  tables  prepared  by  the  Pittsburg 
Reduction  Company  are  given  for  convenient 
reference.  In  Appendix  B  is  given  a  list  of  the 
more  important  aluminum  patents  issued  by  the 
U.  S.  Patent  Office  in  recent  years.  In  Appendix 
C  is  a  tabular  view  of  the  output  of  aluminum  in  the 
United  States,  and  in  Appendix  D  the  cost  per 
pound  of  aluminum. 


ALUMINUM  IN   THE    UNITED  STATES. 
ALUMINUM  WORKS  IN  AMERICA,  1903.* 


Name. 

Location. 

Horse-power. 

Proc- 
ess. 

Capital. 

Avail- 
able. 

In  Use. 

Pittsburg  Red.  Co. 
(Royal  Al.  Co.).  .  . 

Niagara  Falls  

f  14,000 

5,000 

Hall 

$1,600,000 

Massena  Springs,  N.  Y. 
)  Shawenegan    Falls,  1 
1  Quebec,  Canada.  .  .  j 

1,200 
6,000 

*  From  The  Production  of  Aluminum  and  Bauxite,  1903.  By  Joseph 
Struthers,  Washington,  Government  Printing  Office,  1904.  (Extract  from 
Mineral  Resources  of  the  United  States.) 


ALUMINUM  IN   THE   UNITED  STATES. 


251 


APPENDIX   A. 

TABLE  OF  RESISTANCES  OF  PURE  ALUMINUM  WIRE.* 

Conductivity  62  in.  the  Matthiessen  Standard  Scale.     Pure  aluminum  weighs 
167.111  pounds  per  cubic  foot. 


iN 

Resistances  at  70°  F. 

riC/3 

Logd2. 

Log/?. 

.< 

R  Ohms 

Ohms 

Feet 

Ohms  per 

|« 

per  1000 
Feet. 

per  Mile. 

per  Ohm. 

Pound. 

0000 

.07904 

.41730 

12652. 

.00040985 

5.325516 

.897847 

000 

.09966 

.52623 

10034. 

.00065102 

5.224808 

.998521 

00 

.12569 

.66362 

7956. 

.0010364 

5  .  i  24102 

.099301 

0 

.15849 

.83684 

6310. 

.0016479 

5.023394 

.  200002 

I 

.  19982 

1-0552 

5005. 

.0026194 

4.922688 

.300639 

2 

.  25200 

1.3305 

3968. 

.0041656 

4.821980 

.401401 

3 

•31778 

1.6779 

3I47- 

.0066250 

4-721274 

.502127 

4 

.40067 

2.  1156 

2496. 

.010531 

4.620566 

.602787 

5 

.50526 

2.6679 

1975- 

.016749 

4.519860 

.703515 

6 

.63720 

3.3687 

1569. 

.026628 

4.419152 

.804276 

7 

.80350 

1245. 

.042335 

4.318446 

.  904986 

8 

•  o  1  3  1 

5.3498 

987.0 

.067318 

4.217738 

.005652 

9 

•  2773 

6.7442 

783.0 

.  107  10 

4.117030 

.  106293 

10 

.6111 

8.5065 

620.8 

.  17028 

4.016324 

.  207122 

ii 

.0312 

10.723 

492.4 

.  27061 

3.915616 

.307753 

12 

•  5615 

13.525 

390.5 

.43040 

3.814910 

.408494 

13 

3.2300 

17.055 

309-6 

.68437 

3.714202 

.509203 

14 

4.0724 

21  .502 

245-6 

1.0877 

3-613496 

.609850 

IS 

5.1354 

27.  114 

194-8 

1.7308 

3.513788 

.710574 

16 

6.4755 

34.190 

154-4 

2.7505 

3.412082 

.811273 

17 

8.1670 

43-124     . 

122.5 

4-3746 

3.311374 

.912063 

18 

10.  300 

54-388 

97.  10 

6.9590 

3.210668 

.012837 

19 

12.985 

68.564 

77-05 

ii  .070 

3.  109960 

.113442 

20 

16.381 

86.500 

61  .06 

17-595 

3.009254 

.214340 

21 

20  .  649 

109.02 

48.43 

27.971 

908546 

.314899 

22 

26.025 

137-42 

38.44 

44.450 

807838 

.415391 

23 

32.830 

173-35 

30.45 

70.700 

707132 

.516271 

24 

41.400 

218.60 

24.  1  6 

112.43 

606424 

.  61  7000 

25 

52.  200 

275.61 

19.  16 

178.78 

505718 

.717671 

26 

65.856 

347-70 

15-  19 

284-36 

405010 

.818595 

27 

83.010 

438.32 

12.05 

452.62 

304304 

.919130 

28 

104.67 

552.64 

9-55 

7i8.95 

203596 

.019822 

29 

132.00 

697  .01 

7.58 

1142.9 

102890 

.120574 

30 

166.43 

878.80 

6.01 

1817.2 

002182 

.  221232 

31 

209.85 

IIOS.O 

4-77 

2888.0 

901476 

.321909 

32 

264.68 

1397.6 

3.78 

4595-5 

800768 

.422721 

33 

333-68 

I  7  60  .  2 

3-00 

7302.0 

.  700060 

.523330 

34 

420.87 

2222  .  2 

2.38 

i  i  627  . 

599354 

.624148 

35 

530.60 

2801.8 

1.88 

18440. 

.498646 

.724767 

36 

669  .  oo 

3532.5 

1.50 

29352. 

.397940 

.825426 

37 

843-46 

4453-0 

1.19 

46600. 

.297234 

.926064 

38 

1064  .  o 

5618.0 

•  95 

74240. 

.  196526 

3.026942 

39 

1341.2 

7082  .  o 

•  75 

118070. 

.095820 

3.127494 

40 

1691  .  I 

8930.0 

-59 

187700. 

5.99112 

3.  228169 

*  Calculated  on  the  basis  of  Dr.  Matthiessen's  standard,     iz.  :   The  resistance 

of  a  pure  soft   copper  wire  i  meter  long,  having  a  weight     f  i  gram  =  .141729 

International  Ohm  at  o°  C. 

(From  Aluminum  for  Electrical  Conductors',  The  Pittsburgh  Reduction  Co. 

1903,,) 

252          ALUMINUM  IN  THE   UNITED  STATES. 

APPENDIX   B. 

LIST   OF   U.  S.  ALUMINUM    PATENTS. 


Date. 

No. 

Name. 

Patent. 

1881,  July  12 

244234 

Paget-Higgs 

Electrolyzes  cryolite  and  borax. 

1885,  April  7 

315266 

Moses  G.  Farmer 

Electrolyzes    aluminum,    chlo- 

rides, Aiorides,  etc. 

1887,  May  3 

362441 

Richard  Gratzel 

Reduces  by  magnesium  et  al. 

and  electrolysis. 

1888,  Aug.  14 

387876 

Paul  Heroult 

Electrolyzes  alumina. 

1889,  April  2 

400664 
400665 

Charles  M.  Hall 

"          " 

400666 

ii     .11      ii 

"          '  • 

400667 

ii        ii      ii 

*  *          *  * 

400766 

ii        ii      ii 

1891,  Dec.  8 

464933 

Charles  S.  Bradley 

Melts   with    electrolyzing   cur- 

rent. 

1892,  Jan.  5 
1892,  Feb.  2 

466460 
468148 

T.  A.  Edison 
Charles  S.  Bradley 

Electrolyzes  al.  chloride. 
Melts    with    electrolyzing   cur- 

rent. 

1892,  April  19 
1892,  April  26 

4731*8 
473866 

Paul  Heroult 
Charles  S.  Bradley 

Electrolyzes  alumina. 
Electrolysis  with  blast  flame. 

1892,  June  7 

476256 

M.  Emme 

Electrolyzes  alumina. 

1892,  June  14 

476914 

Bernard  Bros. 

Electrolyzes    cryolite    and    so- 

dium fluoride. 

1893,  Aug.  22 
1894,  Jan.  1  6 

503929 
512801 

Joseph  B.  Hall 
Willard  E.  Case 

Electrolyzes  alumina. 
Electrolyzes   al.    sulphate   and 

calcium  fluoride. 

ii            i< 

512802 

"        "      " 

Electrolyzes   al.    sulphate   and 

calcium  fluoride. 

1894,  Oct.  23 

527846 

Waldo  and  Gooch 

Electrolysis  al.  compounds. 

527847 

Gooch  and  Waldo 

'            ' 

527848 

'                     * 

1 

527849 

*                     * 

* 

527850 

'                     ' 

' 

527851 

*                     * 

' 

1894,  Oct.  30 
1896,  June  23 
1897,  March  9 

528365 
562785 
578633 

H.  F.  D.  Schwan 
P.  A.  Gooch 

Electrolysis  aluminous  minerals 
Electrolysis  al.  compounds. 

1899,  Aug.  15 
1901,  April  30 

631253 
673364 

W.  Hoopes 

Purifies  aluminum  electrolytic- 

ally. 

1902,  Dec. 

715625 

Taddei,  G 

Electrolysis.  Decomposes  NaCl 

1903 

732410 

Homan 

at  high  temperature. 
Manufacture  of  silicon  and  al. 

from  silicates  of  alumina. 

1904 

763479 

Gin,  G. 

Electrolyzes     A12S3  .  3Na2S     at 

850°  C. 

1904,  May  24 

760554 

Onda,  Myagoro. 

Manufacture    of     sulphides     of 

aluminum  and  alloys  of  al. 

1904,  Nov.  15 

775o6o 

Blackmore,  H.  S. 

Electrolyzes   al.  oxide   in  com- 

bination. 

ALUMINUM  IN   THE    UNITED   STATES. 


253 


APPENDIX  C. 

TABLE  *  SHOWING  THE  OUTPUT  OF  ALUMINUM  IN 
THE  UNITED  STATES,  1883-1904,  WITH  CURRENT 
MARKET  PRICES. 


Year. 


%antity, 
Q 


Value, 
Dollars. 


Bounds. 

1883 83 

1884.  .  .  .*. 150 

1885* 283 

1886 .     3,ooo 

1887 18,000        59,000 

1888 19,000        65,000 

1889 47.468        97.335 

(incl.  alloys) 

1890 61,281  61,281 

(incl.  alloys) 

1891 150,000  100,000 

(incl.  alloys) 

1892 259,885       172,824 

1893 339.629       266,903 

1894 550,000       316,250 

1895 920,000       464,600 

1896 1,300,000       520,000 

1897 4,000,000      1,500,000 

1898 5,200,000      1,716,000 

1899 6,500,000      1,716,000 

i9oof.  .  .  . 7,150,000      1,920,000 

1901 7,150,000      2,238,000 

1902 7,300,000      2,284,590 

1903 7,500,000      2,284,900 

1904 8,600,000^     2,477,900 

*  Based  on  the  Report  of  the  Department  of  the  Interior,  United  States 
Geological  Survey,  Division  of  Mining  and  Mineral  Resources:  Mineral  Prod- 
ucts of  the  United  States,  Washington. 

t  Statistics  from    1900   to    1003  not  forthcoming  from  manufacturers.     Ob- 
viously the  figures  are  much  too  low. — (Translator's  note.) 
I  Too  low.     Probably  10,000,000. — Translator. 


ALUMINUM    PRODUCTION    IN   THE    UNITED    STATES. 

Based  on  Neumann:   Die  Metalle.     Halle:    Wilhelm  Knapp, 

1904. 

Pounds 
Avoirdupois. 

1888 19,000 

1889 48,000 

1890 60,000 

1891 170,000 

1892 290,000 


Pounds 
Avoirdupois. 


1882 o 

1883 90 

1884 150 

1885 700 

1886 6,600 

1887 18,000 


254          ALUMINUM  IN   THE   UNITED  STATES. 

APPENDIX   D. 
PRICE   OF  ALUMINUM. 


M.  per  kg. 

Cents  per  Ib. 

(wholesale, 
on  Continent). 

(wholesale, 
on  Continent). 

1854  

2400          

259.20 

1855  

IOOO          

108  .00 

1856  

300          

32-9° 

1857  

240          

25.92 

1859  

160         

17-38 

1864  

160         

17-38 

1874  

160        

I7-38 

1878  ...  . 

105        

H-34 

1884  

82-       

8.86 

1885  

74        

7-99 

1886  

7°        

1888  

44        

4-75 

1889  

38        

g      f  Feb  

27  .60  

2.98 

"    \  Sept.  ...'.. 

15-20  

i  .64 

fFeb  
1891  1  July  
I  Nov  

12             

8        
5        

1.30 
86 
54 

1892  

5       "  

54 

1893  

5        

54 

1894  

4        

43 

1895  

3        

32 

1896  

2.60  

28 

1897  

2.50  

.27 

1898  

2  .  2O  

.24 

1899  

2  .  2O  

24 

1900  

2            

.22 

1901  

2            

.22 

[1854-89.  Prices  by  Deville  process,  various  establishments. 
1890—1901.  Prices  Electrolytic  Al.  from  Neiihausen,  Metall- 
gesellschaft  Frankfurt. — From  Die  Metalle,  von  Dr.  Bukhard 
Neumann.  Halle,  Wilhelm  Knapp,  1904.] 

1902  (Pitts.  Red.  Co.),  31-37  cts.  per  Ib.;  1903  (Pitts.  Red. 
Co.),  1904,  1905,  ditto. 

IT-  S,  CUSTOMS  DUTIES  as  follows  (July  i,  1902): 

Aluminum  alloys 8  cts.  (Ib.) 

articles • 45  per  cent 

crude 8  cts.  (Ib.) 

14           plates,  sheets,  bars,  or  rods.  13  cts.  (Ib.) 


ALUMINUM  IN   THE   UNITED  STATES.  255 

LIST   OF   A   FEW   IMPORTANT  TREATISES   AND 
MEMOIRS   ON   ALUMINUM/ 

(By  the  Translator.) 

1859.  Deville,  H.  St.  C.  L' Aluminium;  ses  proprietes,  sa  fa- 
brication et  ses  applications.  Paris.  8°. 

1873.  Biedermann,  R.  Aluminium  und  Aluminium- Verbin- 
dungen.  Vienna  Univ.  Exhibition,  1873;  German  Comm. 
Band  III.  Abt.  I.  Halfte  I.  1875.  8°. 

1873.  Wurtz,  C.  A.     Ueber  die  Fabrikation  des  Aluminiums. 
Vienna  Univ.   Exhibition,    1873;    German  Comm.  Am- 
thicher-Bericht.     Band  III.  Abt.  I.   Halfte  I.      1875.   8°. 

1874.  Tissier,  C.  and  A.     Guide  de  la  recherche,  de  1'extraction 
et  de  la  fabrication  d'Aluminium,  et  des  metaux  alcalins. 
Nouv.  ed.      Paris.      12°. 

1884.  Margottet,   J.     Aluminium.     Fremy,   E.     Encyclopedic 
chimique.     Tome  III.  fasc.  4.     8°. 

1885.  Wierzinski,    S.     Die    Fabrikation   des  Aluminiums  und 
des  Alkali-Metalle.     Vienna,     sm.  8°. 

1887.  Richards,  J.   W.     Aluminium:    its  history,  occurrence, 
properties,   metallurgy,   and   applications,   including  its 
alloys.      Philadelphia.     8°.     [ad  and  3d  Editions  since, 
in  1890  and  1896.] 

1888.  Naccari:  Ueber  die  Specifischen  Warme  einiger  Metalle. 
Beiblatter  zu  den  Annalen  der  Physik.     XII,  p.  326. 

1890.     Wickersheimer.     L' aluminium   et  ses  alliages.     Fremy, 

E.     Encyclopedic  chimique. 
1892.     Le  Verrier,  U.     Etudes  sur  l'aluminium.     Conservatoire 

des  Arts  et  Metiers.     Annales.     2e  Ser.  Tome  IV. 
[1893-97.]     Minet,  A.     L'aluminium.     [I.]  Fabrication,  emploi. 

[II.]  Alliages,  emplois  recents.     Paris,  2  vols.,  sm.  8°. 
1900.     March  3.     Aluminum     Conductivity     Tables,     etc.,     in 

L'Eclairage  Electrique,  XXII. 

1900.  Methoden  und  Resultate  der  Untersuchung  des  Alumi- 
niums und  seiner  Abkommlinge.  Zurich:  Schweizerische 

Polytechnicum,  Austalt  zur  Prufung  von  Baumaterialen. 

Mittheilungen.     Heft   IX.     8°. — Zusammengestellt  von 

Prof.  L.  Tetmajer. 
1902.     Feb.     The    Physical   Properties   of  Certain   Aluminium 

Alloys,    and    Some    Notes    on    Aluminium    Conductors. 

Ernest  Wilson.     Jour.  Inst.  E.  E.,  London,  E.  and  F. 

N.  Spon. 


256  ALUMINUM  IN   THE   UNITED  STATES. 

1903.     Moissonier,  P.     L'aluminium,  ses  proprietes,  ses  appli- 
cations.    Paris.     8°.     (Gatithier-Villars.) 

1903.  Winteler,  F.     Die  Aluminium-Industrie.     Braunschweig 
F.  View  eg  und  Sohn. 

1904.  Borchers,  W.     Electric  Smelting    and    Refining, — Alu- 
minum,— Part  II,  p.  93.     (Trans,  by  W.  G.  McMillan.) 
Lond.  and  Phila. 


SUBJECT-MATTER    INDEX. 


PAGE 

Aeronautics,  aluminum  in 200-201 

Alkali  hydrates,  dissolving  (Davy)    65 

Alloys,  copper-aluminum 162-164 

Alloys,  heavy,  of  aluminum 147-155 

Alloys,  light,  of  aluminum 162 

Alloys,  medium  density,  of  aluminum I55™157 

Alloys,  various  densities,  of  aluminum 157-161 

(See  also  under  Aluminum.) 

Alternating  current,  in  producing  aluminum   56 

Aluminothermy 207 

Aluminum,  alloys  of  various  densities 157-161 

antimony 161 

brass i_|8,  149,  152 

bronze.  . 148-155*  53 

characteristics  of  pure 144 

chemical  methods J-1? 

chromium 171 

-cobalt 156 

compounds,  electrolysis  of  molten 63 

,   copper-aluminum  alloys 162-164 

coppering 187 

electrochemical  methods 2,  17-135 

electroplating 186 

ferro-silicon .,    157 

gilding  and  silvering iSS-igi 

-gold 155,  156 

heavy  alloys  of 147 

industry 136-144 

257 


258  SUBJECT-MATTER  INDEX. 

PAGE 

Aluminum,  light  alloys  of 162 

-nickel 156,  157 

nickel-tin,   nickel-iron,  cobalt,  manganese,  manganese- 
copper-zinc 1 66,  167 

nickel-  (see  also  Nickel),  nickel-copper  (German  silver), 

164,  165 

-palladium 156 

partinium 168 

-platinum 156 

processes  for  producing.     See  Index  of  Proper  Names. 

production  of 137-144.  101,  241  ff. 

quicksilver 171 

silicon,  silver,  tin 169-171 

,  soldering  for 175-186 

-sodium  double  chloride  (Castner) 68 

titanium 167 

tungsten 167,  168 

,  uses  of 191-215 

,  working  of 171-175 

zinc,  cadmium,  bismuth,  antimony 168,  169 

Antimony,  with  aluminum 161,  168,  169 

Arc,  electric,  use  of,  in  production  of  aluminum 47 -55 

Automobile,  use  of  aluminum  in  manufacture  of 193 

Bicycle,  use  of  aluminum  in  manufacture  of 193 

Bismuth  with  aluminum 168 

Boring  aluminum 174 

Brass,  aluminum , 148,  149,  152 

Bronze,  aluminum 53,  148-155 

Cadmium  with  aluminum. 168 

Carbides,  production  of. 35,  36,  44-45,  ^° 

Characteristics  of  pure  aluminum 144 

Chemical  methods  of  producing  aluminum 1-17 

Chemistry,  aluminum  in,  and  metallurgy 201-215 

Chromium  with  aluminum 171,  206,  207 

Cobalt,  alloy  with  aluminum 156,  166 

Commerce,  aluminum  in 192 

Conducting-wire,  aluminum  for 194 

Conductivity,  electrical,  of  aluminum 145-147 

Constants,  electrolytic 89 


SUBJECT-MATTER  INDEX.  259 

PAGE 

Copper-aluminum  alloys 162-164 

Coppering  aluminum 187 

Corundum,  artificial,  production  of 213,  214 

Cost  of  producing  aluminum • 28,  141-144 

Cryolite,  use  of,  in  Netto  process 9,  10 

melting  of 48 

Decomposition-voltage  of  electrolyte  (Minet) 85 

(See  also  Electrolyte  and  Electrolytic.) 

Elasticity  of  copper  and  aluminum  bronze  compared 150 

Electric  furnaces  in  aluminum  production 23-56,  243 

Electrochemical  methods  for  producing  aluminum 1-17 

Electrolytic  processes  for  producing  aluminum 19-21,  56-135 

Electrolyte,  resistance  of. : 99,  100 

Electrothermic  processes  for  producing  aluminum 17,  18,  21-56 

Electroplating  aluminum 186 

Energy,  expenditure  of  (Minet) 112 

Ferro-silicon-aluminum 157 

Field-equipment  utensils  of  aluminum 196 

Filing  and  grooving  aluminum 174,  1 75 

Furnaces,  electric 23~56 

Gilding  and  silvering  aluminum. 188-191 

Gold,  alloy  with  aluminum 155,  156 

Hydrates,  dissolving  alkali,  with  electric  current 65 

Industrial  questions:  supplementary  note  by  author 216-224 

Industry,  aluminum 136-144 

,  use  of  aluminum  in 191-201 

Magnalium  ( Zeiss) 248 

Magnesium-aluminum  (Boudouard) .  159-161 

Manganese  with  aluminum 166,  167,  206 

Metallurgy,  aluminum  in  chemistry  and 201-215 

Military  uses  of  aluminum 195,  196 

Molten  aluminum  compounds,  electrolysis  of 63 

Nickel,  alloy  with  aluminum 156,  157,  164-166,  206 

Oxides,  reduction  of. 37-43 


260  SUBJECT-MATTER  INDEX. 

PAGE 

Palladium,  alloy  with  aluminum 156 

Partinium  with  aluminum . .    168 

Patents.     See  Index  of  Proper  Names. 

Use  of  Heroult 118-120 

Phosphorus,  production  of 201 

Photochemistry,  aluminum  in. 202 

Platinum,  alloy  with  aluminum 156 

Polishing  aluminum 176 

Processes  for  producing  aluminum : 

Chemical  methods 1-17 

Electrochemical  methods 2,  17,  135 

(See  Index  of  Proper  Names.)  • 

Producing  aluminum,  processes  for.      See  above. 

Production  of  aluminum  (statistics) 137-144 

Properties,  mechanical,  of  aluminum 145-147 

Pure  aluminum 144-147 

Pure  metals,  production  of 212,  213 

Quicksilver  with  aluminum 171 

Reducing-agent,  aluminum  as,  in  refining  steel,  etc 202-207 

Reduction  of  aluminum  with  sodium 3 

Regeneration  of  both  in  electrolysis 87-89 

Riveting  aluminum 174 

Rotation  of  electrode  (in  Heroult-Kiliani  furnace) 34 

Salts,  aluminum,  electrolysis  of  dissolved 57-^3 

Ship-construction,  aluminum  in , 196-200 

Silicon  with  aluminum 169 

Silver  with  aluminum , 169 

Silvering  and  gilding  aluminum 188-191 

Sodium,  production  of 6 

Soldering  aluminum 175-186 

Soldering  (Goldschmidt) 214 

Theory,   author's    supplementary  note  with    regard    to    theoretical 

portion  of  the  work 224-239 

Tin  with  aluminum 169-171 

Titanium  with  aluminum 167 

Tungsten  with  aluminum 167,  168 


SUBJECT-MATTER   INDEX.  261 

PAGE 

United  States,  aluminum  in 241  ff. 

Uses  of  aluminum 147,  191-215 

Voltage,  decomposition-,  of  electrolyte 85 

(See  also  Electrolyte  and  Electrolytic.) 

Working  of  aluminum 171-175 

Zinc  with  aluminum 168,  I47~ *49 

Zinc  ores,  reduction  of .' 24 


INDEX   OF   PROPER   NAMES. 


Acheson,  36 

Alliance  Aluminium  Company,  8 
Aluminium  Crown  Metal  Co.,  1 3 
Aluminium-Industrie-Akt.  -  Ges. , 

33,  77,  82,  83,   119,   132,   139 

140,  203 
d'Arlatan,  180 
Arnould,  119 
Arons,  200 
Astfalck,  56 


Bailie,  171 

Baldwin,  14 

Baratier,  199 

Basset,  16 

Bates,  184 

Baud,  230 

Becker,  12 

Becquerel,  .100 

Beketoff,  14,  72 

Berg,  123 

Bernard,  81 

Berthaut,  69 

Berthelot,  23,  114 

Bertram,  59 

Bsrzelius,  2 

Bessemer,  i,  15,  50,  203 

Beuson,  16 

Boguski,  72 

Borchers,  12,  22,  34,  35,  36,  37, 

39,  41,  43,  45,  57,  72 
Bornstein,  209 
Bottiger,  130 


Boudouard,  157,  160 

Bougerel,  14 

Bourbouze,  169,  178 

Bourdais,  183 

Bourgoin,  186 

Boussingault,  207 

Braun,  59 

Brin,  i,  48,  49 

British  Aluminium  Co.,  119,  140 

Brown,  167 

Briinner,  4 

Biicherer,  77,  132 

Bull,  123,  127 

Bullier,  36,  45,  80 

Bunsen,   66,   67,    113,    115 

Burghardt,  59 

C. 

Castner,   i,  5,  6,   7,  8,    12,    138 

Calvet,  1 6 

Carrol,  169 

Chabannes  la  Palice,    173,    196 

Chapelle,  16 

Charpentier-Page,  145,  154,  162, 

178,  179,  199,  200 
Clemmon,  202 
Clerc,  23 
Combes,  206 
Compagnie  des  produits  chimi- 

ques,  140 
Corbelli,  16,  57 
Corbin,  192,  193 
Cothias,  147,  149 
Cowles,  2,  22,  23,  27,  39,  45,  65, 

79,  116,  149 

263 


264 


INDEX   OF  PROPER  NAMES. 


D. 

Daniel,  125 
Davy,  2,  65 
Debray,  149 
Delamothe,  181 
Delecluse,  183 
Depretz,  23 

Deville,  i,  3,  4,  5,  6,  8,  13,  66, 
68,  69,  81,  113,  125,  137,  i38 
Dhiel,  126 
Dingier,  58 
Donny,  4 

Douglas- Dixon,  127 
Dreyfus,  119,  200 
Dulls,  1 6 
Dumont,  195 

E. 

Electric  Construction  Corpora- 
tion, 55 
Escher  Wyss,  200 

F. 

Falk,  59 

Faraday,  19,  100 
Farmer,  51,  73 
Faure,  69 
Faurie,  14 
Favre,  66,  114 
Feldmann,  13,  78 
Felt,  62 
Fery,  171 
Fiertz,  48 
Fleury,  16 
Foucau,  203 
Frei,  120 
Frismuth,  12 

G. 

Gaudin,  69 

Gerard-Lescuyer,  53 

Gerhard,  16 

Gilbert,  193 

Glusmaff,  202 

Godinot,  173 

Goldschmidt,  157,  208-215 

Golting,  190 

Gooch,  2,  132,  133,  134,  135,  185 

Gore,  58 

Grabau,  i,  10,  72 

Graetzel,  71 


rousilliers,  72 
uillet,  157,  159 
^uilloux,  173,  197,  199 

H. 

Haber,  218 
Hall   C   M.,  63,  69,  78,  88,  120, 

121,    122,    140,    221,    222,    223, 
224,    227,    233 

Hall,  J.  B.,  123 

Hammond,  185 

Hampes,  2,  130 

Haurd,  59 

Henderson,  77 

Heraeus,  186 

Herold,  61 

Heroult,  i,  2,  22,  23,  28,  29-33, 
39,  43,  63,  65,  69,  75,  78,  80, 
88,  113,  118,  119,  14°,  J49. 

221,    222,    223,    227,    233 

Hervieu,  193 
Hogg,  204,  205 
Houdaille,  195 
Huber,  119 
Huldschinski,  200 
Hunt,  164    • 

J. 

Japy,-i94 
Jeanson,  59 
Johnson,  23,  53 

K. 

Kagenbusch,  69 
Keep,  120,  204 
Kelvin,  90,  120  . 
Kleiner,  2,  48,  130 
Kiliani,  33,  117,  120,  151 
Knowles,  16 
Krouchkott\  171 

L. 

Landolt,  209 

Langley,  203 

Lautherborn,  16 

Leblanc,  190 

Le  Chatelier,  67,  149,  150 

Lefebvre,  199 

Lejcal,  179 

Lenseigne,  190 

Le  Verrier,   164,   167,  205,  224 


INDEX  OF  PROPER  NAMES. 


265 


Levy,  167 

Leybold,  43 

Lontin,  67,  69,  70,  71,  72,  82 

Lossier,  77,  131 

M. 

Mach,  159 

Malbery,  204 

Mallet,  193 

Marchand,  199 

Mareska,  4 

Margot,  155,   156,   187,   188,  189 

Martin,  203 

Menges,  47 

Merle  &  Comp.,  81,  137 

Michel,  167' 

Minet,  2,  12,  43,  44,  63,  69,  78, 

104,140,157,188,222,  230 
Mitscherlich,  4 
Moissan,   2,   22,   35.,  45,  46,  47, 

80,  207 
Montagne,  14 
Montgelas,  59 
Morin,  3,  81,  137 
Morris,  5,  16 
Moukton,  22 
Mourey,  177 
Munerel,  119 


N. 


Nansen,  61 
Naville,  119 
Netto,   i,  5, 
Nickles,  58 
Nicolai,  184 
Nieverth,  16,  59 
Novel,  179 


138 


O. 

Oerstedt,  2 
Olivers,  183 
Omlot,  130 
Overbeck,  59 

P. 

Parkinson,  159 
Partin,  168,  193 
Pearson,  15 
Pechiney,  1 16,  137 
Peniakoff,  132 
Percy,  5,  8 


Perrot,  207 

Pfleger,  61 

Pichon,  23 

Pittsburg  Reduction  Company, 

140 

Pouthiere,  149 
Pratt,  15 
Poggendorff,  67 

R. 

Reillon,  14 

Reinbold,  59 

Richards,  165,  179,  180,  207 

Riche,  100 

Rietz,  6 1 

Ristori,  120 

Ritto,  207 

Roberts- Austin,  155 

Roche,  1 68 

Roger,  131 

Rogers,  77 

Roman,  R.  and  I.,  167 

Rose,  5,  8,  13 

Rossel,  20 1 

Rousseau,  5 

S. 

Sanderson,  15 
Schaag,  59 
Schindler,  69 
Schneller,  56 
Seidler,  130 
Self,  176 
Senet,  59 
Seymour,  16 
Siemens,   23,   50,    116 
Silbermann,   114 
Smee,  58 

Societe        Electrometallurgique 
Frain^aise,  118,  140,  187,  200 
Societe  Vienne  freres,    in 
Spring,  185 
Stefanite,  2,  16 
Stephen,  15 

T. 

Tacony  Iron  and  Metal  Co.,  61 
Tailor,  180 
Thiving,  182 
Thomes,  57 
Thompson,  13 


266  INDEX   OF  PROPER  NAMES. 


Tilly,  57 

Walter,  59 

Tissandier,  182 

Webster,  i,  13 

Tissier,  5,  155,  164,  207 

Weldon,  7,  16 

Tschernouchouko,  201 

White,  13 

Twining,  59 

Whole,  63 

Wilde,  1  6 

Willson,  43,  44,  80 

. 

Winkler,  78 

Van  Aubel,  157,  161 

Wohler,  i,  2,  3,  159,  167,  171,  206 

Varicle,  193 

Vielhomme,  119 

Y1 

Vorce,  204 

. 

Yarrow,  199 

W. 

Wagner,  179,  190 

Z. 

Waldo,  153 

Zdziarski,  72 

TH- 


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Fuertes's  Water  and  Public  Health i2mo,    i  s< 

Furman's  Manual  of  Practical  Assaying 8vo,    3  ex 

*  Getman's  Exercises  in  Physical  Chemistry i2mo,    2  oc 

Gill's  Gas  and  Fuel  Analysis  for  Engineers i2mo,     i   2; 

Grotenfelt's  Principles  of  Modern  Dairy  Practice.     (Woil.) i2mo,    2  oc 

Hammarsten's  Text-book  of  Physiological  Chemistry.     (Mandel.) 8vo,    4  oc 

Helm's  Principles  of  Mathematical  Chemistry.     (Morgan.) i2mo,     i  sc 

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Hind's  Inorganic  Chemistry 8vo,    3  oc 

*  Laboratory  Manual  for  Students i2mo,     i  oc 

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Text-book  of  Organic  Chemistry.     (Walker  and  Mott.) 8vo,    2  50 

*  Laboratory  Manual  of  Organic  Chemistry.     (Walker.) i2mo,    i  co 

Hopkins' s  Oil-chemists'  Handbook 8vo,    3  oo 

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Keep's  Cast  Iron 8vo,    2  50 

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Matthew's  The  Textile  Fibres 8vo,    3  50 

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Poole's  Calorific  Power  of  Fuels 8vo,    3  oo 

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4 


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Rideal's  Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  3  50 

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Rigg's  Elementary  Manual  for  the  Chemical  Laboratory 8vo,  i  25 

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Salkowski's  Physiological  and  Pathological  Chemistry.  (Orndorff.) 8vo,  2  50 

Schimpf's  Text-book  of  Volumetric  Analysis I2mo,  2  50 

Essentials  of  Volumetric  Analysis i2mo,  i  25 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses i6mo,  morocco,  3  oo 

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*  Walke's  Lectures  on  Explosives 8"o,  4  oo 

Washington's  Manual  of  the  Chemical  Analysis  of  Rocks 8"o,  2  oo 

Wassermann's  Immune  Sera:  Hsemolysins,  Cytotoxins,  and  Precipitins.    (Bol- 
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Well's  Laboratory  Guide  in  Qualitative  Chemical  Analysis 8vo,  i  50 

Short  Course  in  Inorganic  Qualitative  Chemical  Analysis  for  Engineering 

Students ._ 1 2mo ,  i  50 

Text-book  of  Chemical  Arithmetic I2mo,  i  25 

Whipple's  Microscopy  of  Drinking-water '.  .  .  .8vo,  3  50 

Wilson's  Cyanide  Processes I2mo,  i  50 

Chlorination  Process temo,  i  50 

Wulling's    Elementary    Course    in  Inorganic,  Pharmaceutical,  and  Medical 

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CIVIL  ENGINEERING. 

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Davis's  Elevation  and  Stadia  Tables 8vo,  i  oo 

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Freitag's  Architectural  Engineering.     2d  Edition,  Rewritten 8vo,  3  50 

French  and  Ives's  Stereotomy 8vo,  2  50 

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Hayford's  Text-book  of  Geodetic  Astronomy 8vc,  3  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocoo,  2  50 

5 


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Mahan's  Treatise  on  Civil  Engineering.     (1873.)     (Wood.) 8vo,  5  oo 

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Elements  of  Sanitary  Engineering 8vo,  2  oo 

Merriman  and  Brooks's  Handbook  for  Surveyors i6mo,  morocco,  2  oo 

Nugent's  Plane  Surveying 8vo,  3  50 

Ogden's  Sewer  Design i2mo,  2  oo 

Patton's  Treatise  on  Civil  Engineering 8vo  half  leather,  7  50 

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Rideal's  Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  3  50 

Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry. ' 8vo,  i  50 

Smith's  Manual  of  Topographical  Drawing.     (McMillan.) 8vo,  2  50 

Sondericker's  Graphic  Statics,  with  Applications  to  Trusses,  Beams,  and  Arches. 

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Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

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Wait's  Engineering  and  Archi'ectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

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Sheep,  5  5<> 

Law  of  Contracts 8vo,  3  oo 

Warren's  Stereotomy — Problems  in  Stone-cutting 8vo,  2  50 

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*  Wheeler  s  Elementary  Course  of  Civil  Engineering 8vo,  4  oo 

Wilson's  Topographic  Surveying 8vo,  3  50 

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Boiler's  Practical  Treatise  on  the  Construction  of  Iron  Highway  Bridges .  .  8ro,  2  oo 

*  Thames  River  Bridge 4to,  paper,  5  oo 

Burr's  Course  on  the  Stresses  in  Bridges  and  Roof  Trusses,  Arched  Ribs,  and 

Suspension  Bridges 8vo,  3  50 

Burr  and  Felk's  Influence  Lines  for  Bridge  and  Roof  Computations.  .  .  .8vo,  3  oo 

Du  Bois's  Mechanics  of  Engineering.     Vol.  II Small  4to,  10  oo 

Foster's  Treatise  on  Wooden  Trestle  Bridges 4to,  5  oo 

Fowler's  Ordinary  Foundations 8vo,  3  50 

Greene's  Roof  Trusses 8vo,  i  25 

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Arches  in  Wood,  Iron,  and  Stone 8vo,  2  50 

Howe's  Treatise  on  Arches 8vo,  4  oo 

Design  of  Cimple  Roof-trusses  in  Wood  and  Steel 8vo,  2  oo 

Johnson,  Bryan,  and  Turneaure's  Theory  and  Practice  in  the  Designing  of 

Modern  Framed  Structures Small  4to,  10  oo 

JSIerriman  and  Jacoby's  Text-book  on  Roofs  and  Bridges: 

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Part  in.     Bridge  Design 8vo,  2  50 

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Morison's  Memphis  Bridge 4to,  10  oo 

Waddell's  De  Pontibus,  a  Pocket-book  for  Bridge  Engineers.  .  i6mo,  morocco,  3  oo 

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Wood's  Treatise  on  the  Theory  of  the  Construction  of  Bridges  and  Roofs .  .  8vo,  2  oo 
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Two  parts  in  one  volume 8vo,  3  50 

6 


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Church's  Mechanics  of  Engineering 8vo,  6  oo 

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Coffin's  Graphical  Solution  of  Hydraulic  Problems i6mo,  morocco,  2  50 

Flather's  Dynamometers,  and  the  Measurement  of  Power .  i2mo,  3  oo 

Folwell's  Water-supply  Engineering 8vo,  4  oo 

FrizelFs  Water-power 8vo,  5  °° 

Fuertes's  Water  and  Public  Health i2mo,  i  50 

Water-filtration  Works i2mo,  2  50 

Ganguillet  and  Kutter's  General  Formula  for  the  Uniform  Flow  of  Water  in 

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Hazen's  Filtration  of  Public  Water-supply 8vo,  3*  oo 

Hazlehurst's  Towers  and  Tanks  for  Water-works 8vo,  2  50 

Herschel's  115  Experiments  on  the  Carrying  Capacity  of  Large,  Riveted,  Metal 

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*  Michie's  Elements  of  Analytical  Mechanics 8vo,  4  oo 

Schuyler's   Reservoirs   for   Irrigation,   Water-power,   and   Domestic   Water- 
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Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Wegmann's  Design  and  Construction  of  Dams 4to,  5  oo 

Water-supply  of  the  City  of  New  York  from  1658  to  1895 4to,  10  oo 

Williams  and  Hazen's  Hydraulic  Tables 8vo,  i   50 

Wilson's  Irrigation  Engineering Small  8vo,  4  oo 

Wolff's  Windmill  as  a  Prime  Mover -.  .  .  .  8vo,  3  oo 

Wood's  Turbines 8vo,  2  50 

Elements  of  Analytical  Mechanics 8vo,  3  oo 

MATERIALS  OF  ENGINEERING. 

Baker's  Treatise  on  Masonry  Construction 8vo,  5  oo 

Roads  and  Pavements 8vo,  5  oo 

Black's  United  States  Public  Works '..'. Oblong  4to,  5  oo 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering 8vo,  7  50 

Byrne's  Highway  Construction 8vo,  5  oo 

Inspection  of  the  Materials  and  Workmanship  Employed  in  Construction. 

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Church's  Mechanics  of  Engineering 8vo,  6  oo 

Du  Bois's  Mechanics  of  Engineering.     Vol.  I Small  4to,  7  50 

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Johnson's  Materials  of  Construction Large  8vo,  6  oo 

Fowler's  Ordinary  Foundations 8vo,  3  50 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Marten's  Handbook  on  Testing  Materials.     (Henning.)     2  vols 8vo,  7  50 

Merrill's  Stones  for  Building  and  Decoration 8vo,  5  oo 

Merriman's  Mechanics  of  Materials.                                  8vo,  5  oo 

Strength  of  Materials i2mo,  i  oo 

Metcalf's  Steel.     A  Manual  for  Steel-users i2mo,  2  oo 

Patton's  Practical  Treatise  on  Foundations 8vo,  5  oo 

Richardson's  Modern  Asphalt  Pavements 8vo,  3  oo 

Richey's  Handbook  for  Superintendents  of  Construction i6mo,  mor.,  4  oo 

Rockwell's  Roads  and  Pavements  in  France i2mo,  i  25 

7 


Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Materials  of  Machines i2mo,  i  oo 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Spalding's  Hydraulic  Cement i2mo,  2  oo 

Text-book  on  Roads  and  Pavements I2mo,  2  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

Thurston's  Materials  of  Engineering.     3  Parts 8vo,  8  oo 

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Thurston's  Text-book  of  the  Materials  of  Construction 8vo,  5  oo 

Tillson's  Street  Pavements  and  Paving  Materials 8vo,  4  oo 

Waddell's  De  Pontibus.    ( A  Pocket-book  for  Bridge  Engineers.)-  .  i6mo,  mor.,  3  oo 

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Wdod's  (De  V.)  Treatise  on  the  Resistance  of  Materials,  and  an  Appendix  on 

the  Preservation  of  Timber 8vo,  2  oo 

Wood's  (De  V.)  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Wood'.;  (M.  P.)  Rustless  Coatings:    Corrosion  and  Electrolysis  of  Iron  and 

Steel 8vo,  4  oo 

RAILWAY  ENGINEERING. 

Andrew's  Handbook  for  Street  Railway  Engineers 3x5  inches,  morocco,  i  25 

Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  oo 

Brook's  Handbook  of  Street  Railroad  Location i6mo,  morocco,  i  50 

Butt's  Civil  Engineer's  Field-book i6mo,  morocco,  2  50 

Crandall's  Transition  Curve i6mo,  morocco,  i  50 

Railway  and  Other  Earthwork  Tables 8vo,  i  50 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  .  i6mo,  morocco,  5  oo 

Dredge's  History  of  the  Pennsylvania  Railroad:    (1879) Paper,  5  oo 

*  Drinker's  Tunnelling,  Explosive  Compounds,  and  Rock  Drills. 4to,  half  mor.,  25  oo 

Fisher's  Table  of  Cubic  Yards Cardboard,  25 

Godwin's  Railroad  Engineers'  Field-book  and  Explorers'  Guide.  .  .  i6mo,  mor.,  2  50 

Howard's  Transition  Curve  Field-book i6mo,  morocco,  i  50 

Hudson's  Tables  for  Calculating  the  Cubic  Contents  of  Excavations  and  Em- 
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Molitor  and  Beard's  Manual  for  Resident  Engineers .-.  i6mo,  i  oo 

Nagle's  Field  Manual  for  Railroad  Engineers i6mo,  morocco,  3  oo 

Philbrick's  Field  Manual  for  Engineers i6mo,  morocco,  3  oo 

Searles's  Field  Engineering i6mo,  morocco,  3  oo 

Railroad  Spiral i6mo,  morocco,  i  50 

Taylor's  Prismoidal  Formulae  and  Earthwork 8vo,  i  50 

*  Trautwine's  Method  of  Calculating  the  Cube  Contents  of  Excavations  and 

Embankments  by  the  Aid  of  Diagrams 8vo,  2  oo 

The  Field  Practice  of  Laying  Out  Circular  Curves  for  Railroads. 

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Cross-section  Sheet Paper,  25 

Webb's  Railroad  Construction i6mo,  morocco,  5  oo 

Wellington's  Economic  Theory  of  the  Location  of  Railways Small  Svo,  5  oo 

DRAWING. 

Barr's  Kinematics  of  Machinery Svo,  2  50 

*  Bartlett's  Mechanical  Drawing Svo,  3  oo 

*  "                    "                   "        Abridged  Ed Svo,  i  50 

Coolidge's  Manual  of  Drawing Svo,  paper  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  Engi- 
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Durley's  Kinematics  of  Machines Svo,  4  oo 

Emch's  Introduction  to  Projective  Geometry  and  its  Applications Svo.  2  50 


Drafting  Instruments  and  Operations 

Manual  of  Elementary  Projection  Drawing i2mo, 

Manual  of  Elementary  Problems  in  the  Linear  Perspective  of  Form  and 

Shadow i2mo, 

Plane  Problems  in  Elementary  Geometry i2mo, 


Hill's  Text-book  on  Shades  and  Shadows,  and  Perspective 8vo,  2  oo 

Jamison's  Elements  of  Mechanical  Drawing 8vo,  2  50 

Advanced  Mechanical  Drawing 8vo,  2  oo 

Jones's  Machine  Design: 

Part  I.     Kinematics  of  Machinery 8vo,  i  50 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

MacCoxd's  Elements  of  Descriptive  Geometry 8vo,  3  oo 

Kinematics;  or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

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Moyer's  Descriptive  Geometry 8vo,  2  oo 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo,  3  oo 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

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Warren's  Elements  of  Plane  and  Solid  Free-hand  Geometrical  Drawing.  i2mo,  oo 

25 
5« 

oo 
25 

Primary  Geometry i2mo,  75 

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General  Problems  of  Shades  and  Shadows 8vo,  3  oo 

Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

Problems,  Theorems,  and  Examples  in  Descriptive  Geometry 8vo,  2  50 

Weisbach's  Kinematics  and  Power  of  Transmission.    (Hermann  and  Klein)8vo,  5  oo 

Whelpley's  Practical  Instruction  in  the  Ait  of  Letter  Engraving 12 mo,  2  oo 

Wilson's  (H.  M.)  Topographic  Surveying 8vo,  3  50 

Wilson's  (V.  T.)  Free-hand  Perspective 8vo,  2  50 

Wilson's  (V.  T.)  Free-hand  Lettering 8vo,  i  oo 

Woolf's  Elementary  Course  in  Descriptive  Geometry Large  8vo,  3  oo 


ELECTRICITY  AND  PHYSICS. 

Anthony  and  Brackett's  Text-book  of  Physics.     (Magie.) Small  8vo,  3  oo 

Anthony's  Lecture-notes  on  the  Theory  of  Electrical  Measurements.  .  .  . I2mo,  i  oo 

Benjamin's  History  of  Electricity, 8vo,  3  oo 

Voltaic  Cell 8vo,  3  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.     (Boltwood.).Svo,  3  oo 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo,  3  oo 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  i6mo,  morocco,  5  oo 
Dolezalek's   Theory   of   the    Lead   Accumulator    (Storage    Battery).      (Von 

Ende.) I2mo,  2  50 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess.) 8vo,  4  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power I2mo,  3  oo 

Gilbert's  De  Magnete.     (Mottelay.) 8vo,  2  50 

Hanchett's  Alternating  Currents  Explained i2mo,  I  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  50 

Holman's  Precision  of  Measurements 8vo,  2  oo 

Telescopic   Mirror-scale  Method,  Adjustments,  and   Tests.  .  .  .Large  8vo,  75 

Kinzbrunner's  Testing  of  Continuous-Current  Machines 8vo,  2  oo 

Landauer's  Spectrum  Analysis.     (Tingle.) 8vo,  3  oo 

Le  Chatelien's  High-temperature  Measurements.  (Boudouard — Burgess.)  i2mo,  3  oo 

Lob's  Electrolysis  and  Electrosynthesis  of  Organic  Compounds.  (Lorenz  )  i2mo,  i  oo 

9 


*  Lyons's  Treatise  on  Electromagnetic  Phenomena.  Vols.  I.  and  II.  8vo,  each,  6  oo 

*  Michie's  Elements  of  Wave  Motion  Relating  to  Sound  and  Light 8vo,  4  oo 

Niaudet's  Elementary  Treatise  on  Electric  Batteries.     (Fishback.) i2mo,  2  50 

*  Rosenberg's  Electrical  Engineering.     (Haldane  Gee — Kinzbrunner.).  .  .8vo,  i  50 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     Vol.  1 8vo,  2  50 

Thurston's  Stationary  Steam-engines 8vo,  2  50 

*  Tillman's  Elementary  Lessons  in  Heat 8vo,  i  50 

Tory  and  Pitcher's  Manual  of  Laboratory  Physics Small  8vo,  2  oo 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

LAW. 

*  Davis's  Elements  of  Law 8vo,    2  50 

*  Treatise  on  the  Military  Law  of  United  States 8vo,    7  oo 

Sheep,  7  50 

Manual  for  Courts-martial i6mo,  morocco,  i  50 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  8vo,  5  oo 

Sheep,  5  50 

Law  of  Contracts 8vo,  3  oo 

Winthrop's  Abridgment  of  Military  Law I2mo,  2  50 

MANUFACTURES. 

Bernadou's  Smokeless  Powder — Nitro-cellulose  and  Theory  of  the  Cellulose 

Molecule i2mo,  2  50 

Bolland's  Iron  Founder i2mo,  2  50 

"The  Iron  Founder,"  Supplement I2mo,  2  50 

Encyclopedia  of  Founding  and  Dictionary  of  Foundry  Terms  Used  in  the 

Practice  of  Moulding i2mo,  3  oo 

Eissler's  Modern  High  Explosives • 8vo,  4  oo 

Eff rent's  Enzymes  and  their  Applications.     (Prescott.) 8vo,  3  oo 

Fitzgerald's  Boston  Machinist i2mo,  i  oo 

Ford's  Boiler  Making  for  Boiler  Makers i8mo,  i  oo 

Hopkin's  Oil-chemists'  Handbook 8vo,  3  oo 

Keep's  Cast  Iron 8vo,  2  50 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control Large  8vo,  7  50 

Matthews's  The  Textile  Fibres 8vo,  3  50 

Metcalf's  Steel.     A  Manual  for  Steel-users i2mo,  2  oo 

Metcalfe's  Cost  of  Manufactures — And  the  Administration  of  Workshops  8vo,  5  oo 

Meyer's  Mpdern  Locomotive  Construction 4to,  10  oo 

Morse's  Calculations  used  in  Cane-sugar  Factories i6mo,  morocco,  i  50 

*  Reisig's  Guide  to  Piece-dyeing 8vo,  25  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Press-working  of  Metals 8vo,  3  oo 

Spalding's  Hydraulic  Cement i2tno,  2  oo 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses.    . .  .  i6mo,  morocco,  3  oo 

Handbook  for  Sugar  Manufacturers  and  their  Chemists.  .  i6mo,  morocco,  2  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

Thurston's  Manual  of  Steam-boilers,  their  Designs,  Construction  and  Opera- 
tion  8vo,  5  oo 

*  Walke's  Lectures  on  Explosives 8vo,  4  oo 

Ware's  Manufacture  of  Sugar.     (In  press.) 

West's  American  Foundry  Practice i2mo,    2  50 

Moulder's  Text-book i2mo,    2  50 

10 


Wolffs  Windmill  as  a  Prime  Mover 8vo,    3  oo 

Wood's  Rustless  Coatings:   Corrosion  and  Electrolysis  of  Iron  and  Steel.  .8vo,    4  oo 


MATHEMATICS. 

Baker's  Elliptic  Functions 8vo, 

*  Bass's  Elements  of  Differential  Calculus i2mo, 

Briggs's  Elements  of  Plane  Analytic  Geometry i2mo, 

Compton's  Manual  of  Logarithmic  Computations i2mo, 

Davis's  Introduction  to  the  Logic  of  Algebra 8vo, 

*  Dickson's  College  Algebra Large  i2mo, 

*  Introduction  to  the  Theory  of  Algebraic  Equations Large  i2mo, 

Emch's  Introduction  to  Projective  Geometry  and  its  Applications 8vo, 

Halsted's  Elements  of  Geometry 8vo, 

Elementary  Synthetic  Geometry „ 8vo, 

Rational  Geometry i2mo, 

*  Johnson's  (J.  B.)  Three-place  Logarithmic  Tables:   Vest-pocket  size. paper,         15 

100  copies  for    5  oo 

*  Mounted  on  heavy  cardboard,  8X 10  inches,        25 

10  copies  for  2  oo 

Johnson's  (W.  W.)  Elementary  Treatise  on  Differential  Calculus .  .  Small  8vo,  3  oo 

Johnson's  (W.  W.)  Elementary  Treatise  on  the  Integral  Calculus.  Small  8vo,  i  50 

Johnson's  (W.  W.)  Curve  Tracing  in  Cartesian  Co-ordinates i2mo,  i  oo 

Johnson's  (W.  W.)  Treatise  on  Ordinary  and  Partial  Differential  Equations. 

Small  8vo,  3  50 

Johnson's  (W.  W.)  Theory  of  Errors  and  the  Method  of  Least  Squares.  i2mo,  i  50 

*  Johnson's  (W.  W.)  Theoretical  Mechanics I2mo,  3  oo 

Laplace's  Philosophical  Essay  on  Probabilities.     (Truscott  and  Emory.).  12010,  2  oo 

*  Ludlow  and  Bass.     Elements  of  Trigonometry  and  Logarithmic  and  Other 

Tables 8vo,  3  oo 

Trigonometry  and  Tables  published  separately Each,  2  oo 

*  Ludlow's  Logarithmic  and  Trigonometric  Tables 8vo,  i  oo 

Maurer's  Technical  Mechanics 8vo,  4  oo 

Merriman  and  Woodward's  Higher  Mathematics.  , 8vo,  5  oo 

Merriman's  Method  of  Least  Squares 8vo,  2  oo 

Rice  and  Johnson's  Elementary  Treatise  on  the  Differential  Calculus. .  Sm.  8vo,  3  oo 

Differential  and  Integral  Calculus.     2  vols.  in  one Small  8vo,    2  50 

Wood's  Elements  of  Co-ordinate  Geometry 8vo,    2  oo 

Trigonometry:  Analytical,  Plane,  and  Spherical i2mo,     i  oo 


MECHANICAL  ENGINEERING. 

MATERIALS  OF  ENGINEERING,  STEAM-ENGINES  AND  TOILERS. 

Bacon's  Forge  Practice i2mo,  i  50 

Baldwin's  Steam  Heating  for  Buildings I2mo,  2  50 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

"        Abridged  Ed 8vo,  i  50 

Benjamin's  Wrinkles  and  Recipes i2mo,  2  oo 

Carpenter's  Experimental  Engineering 8vo,  6  oo 

Heating  and  Ventilating  Buildings 8vo,  4  oo 

Cary's  Smoke  Suppression  in  Plants  using  Bituminous  Coal.     (In  Prepara- 
tion.) 

Clerk's  Gas  and  Oil  Engine Small  8vo,  4  oo 

Coolidge's  Manual  of  Drawing 8vo,  paper,  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  En- 
gineers  Oblong  4to,  2  50 

11 


Cromwell's  Treatise  on  Toothed  Gearing i2mo,  i  50 

Treatise  on  Belts  and  Pulleys i2mo,  i  50 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Flather's  Dynamometers  and  the  Measurement  of  Power i2mo,  3  oo 

Rope  Driving lamo,  2  oo 

Gill's  Gas  and  Fuel  Analysis  for  Engineers i2mo,  i  25 

Hall's  Car  Lubrication I2mo,  i  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  50 

Button's  The  Gas  Engine .".... 8vo,  5  oo 

Jamison's  Mechanical  Drawing 8vo,  2  50 

Jones's  Machine  Design : 

Part  I.     Kinematics  of  Machinery 8vo,  i  50 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

Kent's  Mechanical  Engineers'  Pocket-book i6mo,  morocco,  5  oo 

Kerr's  Power  and  Power  Transmission 8vo,  2  oo 

Leonard's  Machine  Shop,  Tools,  and  Methods 8vo,  4  oo 

*Lorenz's  Modern  Refrigerating  Machinery.     (Pope,  Haven,  and  Dean.)  .  .  8vo,  4  oo 

MacCord's  Kinematics;   or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

Velocity  Diagrams 8vo,  i  50 

Mahan's  Industrial  Drawing.     (Thompson.) 8vo,  3  50 

Poole  s  Calorific  Power  of  Fuels 8vo,  3  oo 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo,  3  oo 

Richard's  Compressed  Air i2mo,  i  50 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Smith's  Press-working  of  Metals 8vo,  3  oo 

Thurston's   Treatise   on   Friction  and   Lost  Work   in   Machinery   and   Mill 

Work 8vo,  3  oo 

Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics .  i2mo,  i  oo 

Warren's  Elements  of  Machine  Construction  and  Drawing ,  .  .  .8vo,  7  50 

Weisbach's    Kinematics    and    the    Power    of    Transmission.     (Herrmann — 

Klein.) 8vo,  5  oo 

Machinery  of  Transmission  and  Governors.     (Herrmann — Klein.).  .8vo,  5  oo 

Wolff's  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Wood's  Turbines 8vo,  2  50 


MATERIALS   OF   ENGINEERING. 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering.    6th  Edition. 

Reset 8vo,  7  50 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Johnson's  Materials  of  Construction 8vo,  6  oo 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  So 

Martens's  Handbook  on  Testing  Materials.     (Henning.) 8vo,  7  So 

Merriman's  Mechanics  of  Materials.  8vo,  5  oo 

Strength  of  Materials I2mo,  i  oo 

Metcalf's  Steel.     A  manual  for  Steel-users I2mo.  2  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Materials  of  Machines I2mo,  i  oo 

Thurston's  Materials  of  Engineering 3  vols.,  8vo,  8  oo 

Part  II.     Iron  and  Steel 8vo,  3  5<> 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo»  2  50 

Text-book  of  the  Materials  of  Construction 8vo,  5  oo 

12 


Wood's  (De  V.)  Treatise  on  the  Resistance  of  Materials  and  an  Appendix  on 

the  Preseivation  of  Timber 8vo,    2  oo 

Wood's  (De  V.)  Elements  of  Analytical  Mechanics 8vo,    3  oo 

Wood's  (M.  P.)  Rustless  Coatings:    Corrosion  and  Electrolysis  of  Iron  and 

Ste»L  .  8vo,    4  oo 


STEAM-ENGINES  AND  BOILERS. 


Berry's  Temperature-entropy  Diagram izmo,  25 

Carnot's  Reflections  on  the  Motive  Power  »f  Heat.     (Thurston.) i2mo,  50 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  .  .  .i6mo,  mor.,  oo 

Pord's  Boiler  Making  for  Boiler  Makers i8mo,  oo 

Goss's  Locomotive  Sparks 8vo,  oo 

Hemenway's  Indicator  Practice  and  Steam-engine  Economy i2mo,  oo 

Button's  Mechanical  Engineering  of  Power  Plants 8vo,  5  oo 

Heat  and  Heat-engines 8vo,  5  oo 

Kent's  Steam  boiler  Economy 8vo,  4  oo 

Kneass's  Practice  and  Theory  of  the  Injector 8vo,  i  50 

MacCord's  Slide-valves 8vo,  2  oo 

Meyer's  Modern  Locomotive  Construction 4to,  10  oo 

Peabody's  Manual  of  the  Steam-engine  Indicator i2mo.  i  50 

Tables  of  the  Properties  of  Saturated  Steam  and  Other  Vapors 8vo,  i  oo 

Thermodynamics  of  the  Steam-engine  and  Other  Heat-engines 8vo,  5  oo 

Valve-gears  for  Steam-engines 8vo,  2  50 

Peabody  and  Miller's  Steam-boilers 8vo,  4  oo 

Pray's  Twenty  Years  with  the  Indicator Large  8vo,  2  50 

Pupin's  Thermodynamics  of  Reversible  Cycles  in  Gases  and  Saturated  Vapors. . 

(Osterberg.) i2mo,  i  25 

Reagan's  Locomotives:  Simple   Compound,  and  Electric i2mo,  2  50 

Rontgen's  Principles  of  Thermodynamics.     (Du  Bois.) 8vo,  5  oo 

Sinclair's  Locomotive  Engine  Running  and  Management i2mo,  2  oo 

Smart's  Handbook  of  Engineering  Laboratory  Practice 12 mo,  2  50 

Snow's  Steam-boiler  Practice 8vo,  3  oo 

Spangler's  Valve-gears 8vo,  2  50 

Notes  on  Thermodynamics i2mo,  i  oo 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,  3  oo 

Thurston's  Handy  Tables 8vo.  i  50 

Manual  of  the  Steam-engine 2  vols.,  8vo,  10  oo 

Part  I.     History,  Structure,  and  Theory 8vo,  6  oo 

Part  II.     Design,  Construction,  and  Operation 8vo,  6  oo 

Handbook  of  Engine  and  Boiler  Trials,  and  the  Use  of  the  Indicator  and 

the  Prony  Brake 8vo,  5  oo 

Stationary  Steam-engines 8vo,  2  50 

Steam-boiler  Explosions  in  Theory  and  in  Practice i2mo,  i  50 

Manual  of  Steam-boilers,  their  Designs,  Construction,  and  Operation 8vo,  5  oo 

Weisbach's  Heat,  Steam,  and  Steam-engines.     (Du  Bois.) 8vo,  5  oo 

Whitham's  Steam-engine  Design 8vo,  5  oo 

Wilson's  Treatise  on  Steam-boilers.     (Flather.) i6mo,  2  50 

Wood's  Thermodynamics,  Heat  Motors,  and  Refrigerating  Machines.  .  .8vo,  4  oo 


MECHANICS  AND  MACHINERY. 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Chase's  The  Art  of  Pattern-making ». . . .  121110,  2  50 

Church!s  Mechanics  of  Engineering 8vo,  6  oo 

15 


Church's  Notes  and  Examples  in  Mechanics 8vo,  2  oo 

Compton's  First  Lessons  in  Metal-working i2mo,  i  50 

Compton  and  De  Groodt's  The  Speed  Lathe i2mo,  i  50 

Cromwell's  Treatise  on  Toothed  Gearing i2mo,  i  50 

Treatise  on  Belts  and  Pulleys i2mo,  i  50 

Dana's  Text-book  of  Elementary  Mechanics  for  Colleges  and  Schools.  .  i2mo,  i  50 

Dingey's  Machinery  Pattern  Making i2mo,  2  oo 

Dredge's  Record  of  the  Transportation  Exhibits  Building  of  the  World's 

Columbian  Exposition  of  1893 4to  half  morocco,  5  oo 

Du  Bois's  Elementary  Principles  of  Mechanics: 

Vol.     I.     Kinematics 8vo,  3  50 

Vol.    II.     Statics 8vo,  4  oo 

Vol.  III.     Kinetics 8vo,  3  50 

Mechanics  of  Engineering.     Vol.    I Small  4to,  7  50 

VoL  II Small  4to,  10  oo 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Fitzgerald's  Boston  Machinist i6mo,  i  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Rope  Driving i2mo,  2  oo 

Goss's  Locomotive  Sparks 8vo,  2  oo 

Hall's  Car  Lubrication i2mo,  i  oo 

Holly's  Art  of  Saw  Filing i8mo,  75 

James's  Kinematics  of  a  Point  and  the  Rational  Mechanics  of  a  Particle.  Sm.8vo,2  oo 

*  Johnson's  (W.  W.)  Theoretical  Mechanics I2mo,  3  oo 

Johnson's  (L.  J.)  Statics  by  Graphic  and  Algebraic  Methods 8vo,  2  oo 

Jones's  Machine  Design: 

Part   I.     Kinematics  of  Machinery 8vo,  i  50 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vc,  3  oo 

Kerr's  Power  and  Power  Transmission 8vo,  2  oo 

Lanza's  Applied  Mechanics 8vo,  7  50 

Leonard's  Machine  Shop,  Tools,  and  Methods 8vo,  4  oo 

*Lorenz's  Modern  Refrigerating  Machinery.      (Pope,  Haven,  and  Dean.). 8vo,  4  oo 

MacCord's  Kinematics;  or,  Practical  Mechanism 8vo,  5  oo 

Velocity  Diagrams 8vo,  i  50 

Maurer's  Technical  Mechanics 8vo,  4  oo 

Merriman's  Mechanics  of  Materials 8vo,  5  oo 

*  Elements  of  Mechanics i2mo,  i  oo 

*  Michie's  Elements  of  Analytical  Mechanics 8vo,  4  oo 

Reagan's  Locomotives:  Simple,  Compound,  and  Electric i2mo,  2  50 

Reid's  Course  in  Mechanical  Drawing 8vo ,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo,  3  oo 

Richards's  Compressed  Air i2mo,  i  50 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     VoL  1 8vo,  2  50 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Sinclair's  Locomotive-engine  Running  and  Management 12 mo,  2  oo 

Smith's  (O.)  Press-working  of  Metals 8vo,  3  oo 

Smith's  (A.  W.)  Materials  of  Machines I2mo,  i  oo 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,  3  oo 

Thurston's  Treatise  on  Friction  and  Lost  Y/ork  in    Machinery  and    Mill 

Work 8vo,  3  oo 

Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics, 

12010,  I    OO 

Warren's  Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

Weisbach's  Kinematics  and  Power  of  Transmission.  (Herrmann — Klein. ) .  8vo ,  5  oo 

Machinery  of  Transmission  and  Governors.  (Herrmann — Klein. ).8vo,  5  oo 

Wood's  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Principles  of  Elementary  Mechanics I2mo,  i  25 

Turbines 8vo,  2  50 

The  World's  Columbian  Exposition  of  1893 4to,  i  oo 

14 


METALLURGY. 

Egleston's  Metallurgy  of  Silver,  Gold,  and  Mercury: 

Vol.    i.     Silver 8vo,  7  SO 

Vol.  II.     Gold  and  Mercury 8vo,  7  5<> 

**  Iles's  Lead-smelting.     (Postage  9  cents  additional.) I2mo,  2  50 

Keep's  Cast  Iron 8vo,  2  50 

Earnhardt's  Practice  of  Ore  Dressing  in  Europe .8vo,  i  50 

Le  Chatelier's  High-temperature  Measurements.  (Boudouard — Burgess.  )i2mo,  3  oo 

Metcalf' s  Steel.     A  Manual  for  Steel-users-     i2mo,  2  oo 

Smith's  Materials  of  Machines 12010,  i  oo 

Thurston's  Materials  of  Engineering.     In  Three  Parts 8vo  8  oo 

Part    II.     Iron  and  Steel 8vo.  3  5° 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Hike's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

MINERALOGY. 

Barringer's  Description  of  Minerals  of  Commercial  Value.    Oblong,  morocco,  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo,  3  oo 

Map  of  Southwest  Virignia Pocket-book  form.  2  oo 

Brush's  Manual  of  Determinative  Mineralogy.     (Penfield.) 8vo,  4  oo 

Chester's  Catalogue  of  Minerals 8vo,  paper,  i  oo 

Cloth,  i  25 

Dictionary  of  the  Names  of  Minerals 8vo,  3  50 

Dana's  System  of  Mineralogy Large  8vo,  half  leather,  12  50 

First  Appendix  to  Dana's  New  "  System  of  Mineralogy." Large  8vo,  i  oo 

Text-book  of  Mineralogy 8vo,  4  oo 

Minerals  and  How  to  Study  Them I2tno,  i  50 

Catalogue  of  American  Localities  of  Minerals Large  8vo,  i  oo 

Manual  of  Mineralogy  and  Petrography i2mo ,  2  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects 12010,  i  oo 

Eakle's  Mineral  Tables 8vo,  i  25 

Egleston's  Catalogue  of  Minerals  and  Synonyms '. 8vo,  2  50 

Hussak's  The  Determination  of  Rock-forming  Minerals.    (Smith. ).  Small  8vo,  2  oo 

Merrill's  Non-metallic  Minerals:  Their  Occurrence  and  Uses 8vo,  4  oo 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo  paper,  o  50 
Rosenbusch's   Microscopical   Physiography   of   the   Rock-making  Minerals. 

(Iddings.) 8vo,  5  oo 

*  Tillman's  Text-book  of  Important  Minerals  and  Rocks .8vo.  2  oo 

Williams's  Manual  of  Lithology 8vo,  3  oo 

MINING. 

Beard's  Ventilation  of  Mines I2mo.  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo.  3  oo 

Map  of  Southwest  Virginia Pocket  book  form,  2  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects I2mo.  i  oo 

*  Drinker's  Tunneling,  Explosive  Compounds,  and  Rock  Drills.  .4to,hf.  mor  .  25  oo 

Eissler's  Modern  High  Explosives. 8vo,  4  oo 

Fowler's  Sewage  Works  Analyses 12010,  2  oo 

Goodyear's  Coal-mines  of  the  Western  Coast  of  the  United  States i2mo,  2  50 

Ihlseng's  Manual  of  Mining .8vo.  5  oo 

**  Iles's  Lead-smelting.     (Postage  oc.  additional.} ~ i2mo.  2  50 

Kunhardt's  Practice  of  Ore  Dressing  in  Europe 8vo,  i  50 

O'DriscolTs  Notes  on  the  Treatment  of  Gold  Ores 8vo.  2  oo 

*  Walke's  Lectures  on  Explosives 8vo,    4  oo 

Wilson's  Cyanide  Processes , I2mo,     i  50 

Chlorination  Process izmo,    i  50 

15 


Wilson's  Hydraulic  and  Placer  Mining i2mo  2 

Treatise  on  Practical  and  Theoretical  Mine  Ventilation T2mo',  i   25 

SANITARY  SCIENCE. 

Bashore's  Sanitation  of  a  Country  House I2mo,  i  oo 

Folwell's  Sewerage.     (Designing,  Construction,  and  Maintenance.) 8vo',  3  oc 

Water-supply  Engineering 8vo,  4  oo 

Fuertes's  Water  and  Public  Health. i2mo,  i  50 

Water-filtration  Works "  '  '  '  I2mo!  2  50 

Gerhard's  Guide  to  Sanitary  House-inspection i6mo!  i  oo 

Goodrich's  Economic  Disposal  of  Town's  Refuse Demy  8vo,  3  50 

Hazen's  Filtration  of  Public  Water-supplies 8vo,  3  oo 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Cont™l 8vo,  7  50 

Mason's  Water-supply.  (Considered  principally  from  a  Sanitary  Standpoint)  8vo,  4  oo 

Examination  of  Water.     (Chemical  and  Bacteriological.) izmo,  i  25 

Merriman's  Elements  of  Sanitary  Engineering 8vo,  2  oo 

Ogden's  Sewer  Design I2mo'  2  oo 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis i2mo,  i  25 

*  Price's  Handbook  on  Sanitation i2mo,  i  50 

Richards's  Cost  of  Food.     A  Study  in  Dietaries i2mo,  i  oo 

Cost  of  Living  as  Modified  by  Sanitaiy  Science i2mo,  i  oo 

Richards  and  Woodman's  Air,  Water,  and  Food  from  a  Sanitary  Stand- 
point  r. .  .8vo,  2  oo 

*  Richards  and  Williams's  The  Dietary  Computer 8vo,  i  50 

Rideal's  Sewage  and  Bacterial  Purification  of  Sewage 8vo,  3  50 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Von  Behring's  Suppression  of  Tuberculosis.     (Bolduan.) 12010,  i  oo 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Woodhull's  Notes  on  Military  Hygiene i6mo,  i  50 

MISCELLANEOUS. 

De  Fursac's  Manual  of  Psychiatry.  (Rosanoff  and  Collins.).  ..  .Large  i2mo,  2  50 
Emmons's  Geological  Guide-book  of  the  Rocky  Mountain  Excursion  of  the 

International  Congress  of  Geologists Large  8vo,  i  50 

Ferrel's  Popular  Treatise  on  the  Winds 8vo.  4  oo 

Haines's  American  Railway  Management i2mo,  2  50 

Mott's  Composition,  Digestibility,  and  Nutritive  Value  of  Food.  Mounted  chart,  i  25 

Fallacy  of  the  Present  Theory  of  Sound i6mo,  i  oo 

Ricketts's  History  of  Rensselaer  Polytechnic  Institute,  1824-1894.  .Small  8vo,  3  oo 

Rostoski's  Serum  Diagnosis.  (Bolduan.) i2mo,  i  oo 

Rotherham's  Emphasized  New  Testament Large  8vo,  2  oo 

Steel's  Treatise  on  the  Diseases  of  the  Dog 8vo,  3  50 

Totten's  Important  Question  in  Metrology 8vo,  2  50 

The  World's  Columbian  Exposition  of  1893 4to,  i  oo 

Von  Behring's  Suppression  of  Tuberculosis.  (Bolduan.) i2mo,  i  oo 

Winslow's  Elements  of  Applied  Microscopy i2mo,  i  50 

Worcester  and  Atkinson.  Small  Hospitals,  Establishment  and  Maintenance; 

Suggestions  for  Hospital  Architecture :  Plans  for  Small  Hospital .  1 2  mo ,  125 

HEBREW  AND  CHALDEE  TEXT-BOOKS. 

Green's  Elementary  Hebrew  Grammar I2mo,  i  25 

Hebrew  Chrestomathy : 8vo,  a  oo 

Gesenius's  Hebrew  and  Chaldee  Lexicon  tr   the  Old  Testament  Scriptures. 

(Tregelles.) Small  4to,  half  morocco,  5  oo 

Lettenis's  Hebrew  Bible 8vo,  2  25 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 

Return  to  desk  from  which  borrowed. 
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***  « 

FEB  2  1  1954  LU 


LIBRARY  USE 

APR  2  9  1961 

REC'D  LD 

APR  29  1961 


EC'D  LD 

J|N12'64-8AM 

1960 


yunt 


LD  21-100m-91'48(B399sl6)476 


